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The evil 2 prong plug.

jh45gun
July 20th, 2008, 12:45 PM
Now before you all shoot the poster I have converted my Silvertone 1472 to a 3 prong plug as I have my 5e3 build. I post this as a poster at the Gear Page said his amp tech of 40 plus years expirience would not convert the guys blond blond bandmaster to a 3 prong plug. Now my amp tech as many here know as I posted a reference to this before does not believe in changeing them over either. He said you plug in your amp and listen to it then reverse the plug and plug it in and listen to it again. which ever way is quieter is the proper way for that wireing of the place your in. He says a 3 prong plug will not save you if the wireing is wrong to begin with. Now this got me to thinking so why do amps have the bad rep and are such a concern over other two prong thigs we use every day with out a thought? Lamps come to mind as household appliances, electric tools, radios ect. I would bet more folks have been killed messing with toasters and lightbulbs than amps

ramseybella
July 20th, 2008, 12:54 PM
But you’re not constantly handling an electric toasters, and lamps like say your steel string Electric guitar it never leaves -your arms!!
Ever play your guitar barefooted on a cement floor with a two prong plug and lay a sweaty arm across your bridge? {BuZZZZZ!!} You become ground.
Consider the charge a Capacitors holds as well.

SamBooka
July 20th, 2008, 01:02 PM
I dont know anyone who doesnt recommend installing a 3 prong plug.
With vintage amps (unless they are collection pieces) you need to change certain components anyway (filter caps etc) so if you want the amp to sound good you do have to change parts. Hang on to the old cord (and have the death cap removed.. save it too). If you want to sell you can allways put it back in. I had used a two prong plug for years on my tremolux (just changed it this spring but i never use the amp anymore). I never remember a difference in hum or tone depending on the polarity switch on the back.
I DO remember paying my bass player a beer every gig to touch my strings and mic at the same time.. if there was a shock I would flick the polarity switch.
I am NOT an expert...

Cheers
Drew

SamBooka
July 20th, 2008, 01:03 PM
But you’re not constantly handling an electric toasters, and lamps like say your steel string Electric guitar it never leaves -your arms!!
Ever play your guitar barefooted on a cement floor with a two prong plug and lay a sweaty arm across your bridge? {BuZZZZZ!!} You become ground.
Consider the charge a Capacitors holds as well.

I was going to include the socked feet on bare concrete thing too.. never got a shock but just a very uncomfortable feeling.. put your sneakers back on :)

voodoostation
July 20th, 2008, 01:07 PM
:twisted: I look at it more as a means of reducing the chances of you looking like a squirrel after french kissing a transformer. Any means you can find to keep from getting electrocuted, the better. As a footnote, the U.S. Navy never grounds any of the large electrical components on their ships, because the sailors are expendable and the boat ain't. Are you expendable?:mrgreen:

SamBooka
July 20th, 2008, 01:32 PM
I have never tried this.. but if you insist.
This is from Customizing your Electric Guitar by Adrian Legg.
Dont know what effect on tone it has.. dont think any.

wire a 220k resistor in parallel with a .001 capacitor (assuming microfarads.. I could be wrong tho). Lift the ground from the strings and put this in series with the bridge and the ground...

Make sense?
If not let me know.. I will be more clear.

Gunny
July 20th, 2008, 01:48 PM
I worked an entire career in electrical and electronics and have accrediation in each. I would absolutely never agree with anyone who refuses to install a hard wired ground to a guitar amp chassis.
If the power cable ground is properly installed, it will always be safe to touch the amp, guitar and strings. Period.
How can anyone, in this modern age, imagine a house or any other structure, wired with a "hot" ground?? If that were the case, sure you'd get a shock. I find it impossible to imagine receptacle wiring to be that screwed up. If in doubt, use a receptacle checker first. 2 wire power cords for guitar amps are archaic and dangerous. Do NOT bet your life on a 2 wire power cord.

BTW a 220k resistor in parallel with a .001 capacitor in the guitar is a "work around" and doesn't address the principle problem. I recommend leaving the instrument(s) as is and ensuring the amp is safe to touch.

fakeocaster
July 20th, 2008, 02:02 PM
using a 2 wire plug only works if you can completly trust the insulation integrity,and gives no advantage over a properly grounded system.

Its stupid to take chances with your safety:If I were you I'd get a tech with a better grasp of electrical safety

surfoverb
July 20th, 2008, 02:06 PM
Eric Johnson converts his amps (twins) to 2 prong if they're not already.

jhegel
July 20th, 2008, 02:19 PM
Now this got me to thinking so why do amps have the bad rep and are such a concern over other two prong thigs we use every day with out a thought? Lamps come to mind as household appliances, electric tools, radios ect. I would bet more folks have been killed messing with toasters and lightbulbs than amps

In the U.S. lamps and other household appliances that have two prong plugs and are of modern design come with polarized plugs. One side will be larger than the other. This prevents you from plugging them in the wrong way.

Common sense tells us to install three prong plugs on amps. Anything that can prevent fatal shock is a good thing. Always check your outlet you plug into to assure that it is properly wired. A simple checker costs around $5.00 and can easily rattle around in the bottom of your amp.

30 years as a master electrician and 15 years as an electrical inspector I've seen alot of preventable accidents. If you choose not to fix the problem it is no longer an accident if and when someone gets shocked/electrocuted.

emu!
July 20th, 2008, 02:22 PM
I totally agree that a 3 prong plug is a safety necessity.

Not knowing alot about electricity, I am still confused on how an electrical device could EVEN WORK properly when a 2 blade plug is turned "upside down"???? I mean...on a standard wall outlet, one blade is HOT...one blade is NEUTRAL, and the round prong is EARTH GROUND...right??? Flipping the plug upside down will feed the electrical device a nuetral signal when it is expecting a hot AC signal...right??? The device shouldn't even work at all if logic applies. What am I missing???

:confused: :confused:

vjf1968
July 20th, 2008, 02:53 PM
Eric Johnson converts his amps (twins) to 2 prong if they're not already.

No offense, but just because Eric Johnson does something is not a license for you to do it to. Eric Johnson has his own crew and probably a separate power supply set up which allows him to use a 2 prong cord from the amp but have a grounded power supply unit that keeps everything safe. Also, there is also the technical rider in his contracts which states power requirements and proper wiring.
I use to do monitor mixes for a cover band that played the Philly and Jersey shore circuit. The sound guy also had his own electrician who would tap into the power junction box at the venue and run the line through their own power supply to the stage to power lights and sound (off of separate circuits) so everything ran safe and efficient.

voodoostation
July 20th, 2008, 03:15 PM
Emu, it's more about the path of the circuit then the polarity. On older equipment, polarity wasn't important or necessary. When electronics started showing up, polarity became an issue, due to transistors, diodes, all that solid state magic stuff. In older circuitry (two wire), the white, or common actually went to a building ground. When you reverse that, all your normally neutral lines become hot and potentially very dangerous. Equipment like amps and recievers, and stuff with different voltages internally use the same initial neutral in the circuit. Think of it as a line that you would clip onto if you were on scaffold to keep from falling off. If you put a potential (voltage) on that line, you get bit.

Tim Armstrong
July 20th, 2008, 03:17 PM
Eric Johnson converts his amps (twins) to 2 prong if they're not already.

Eric Johnson is, well, crazy!

Cheers, Tim

voodoostation
July 20th, 2008, 03:20 PM
Eric Johnson is, well, crazy!

Amen brother!!

jh45gun
July 20th, 2008, 03:25 PM
Eric Johnson converts his amps (twins) to 2 prong if they're not already.


Would you happen to know why?

jh45gun
July 20th, 2008, 03:26 PM
In the U.S. lamps and other household appliances that have two prong plugs and are of modern design come with polarized plugs. One side will be larger than the other. This prevents you from plugging them in the wrong way.

Common sense tells us to install three prong plugs on amps. Anything that can prevent fatal shock is a good thing. Always check your outlet you plug into to assure that it is properly wired. A simple checker costs around $5.00 and can easily rattle around in the bottom of your amp.

30 years as a master electrician and 15 years as an electrical inspector I've seen alot of preventable accidents. If you choose not to fix the problem it is no longer an accident if and when someone gets shocked/electrocuted.

Yea and there are still a lot of things out there that have 2 prong plugs that are not polarized too and they are modern stuff so not every one uses polarized plugs on their products.

Tim Armstrong
July 20th, 2008, 03:27 PM
Would you happen to know why?

Probably for the same reason that he labels all of his patch cables so they always go the same way, because he hears a difference (or at least THINKS he hears a difference). He's kinda legendary for his rather extreme fixation on the very tiniest possible variables....

Like I said, he's crazy!

:mrgreen:

Cheers, Tim

jh45gun
July 20th, 2008, 03:33 PM
Trust me I am not saying the 3 prong is wrong I have converted my own stuff all I am saying is that there are cases of two prong stuff being used out there besides amps everyday that then could have the same potential to kill ya like my lamps and toaster comparison and there are techs out there that do not like to use them 3 prong plugs on amps for what ever the reason. I know one and woozy at the gear page knows one I would suspect there are certainly more out there. These folks also have been in business for a long time and are not afraid of giving this advice or worried about law suits so who is right and who is wrong hard to say as this is one of those continual debate issues. Jim

emu!
July 20th, 2008, 03:47 PM
Emu, it's more about the path of the circuit then the polarity. On older equipment, polarity wasn't important or necessary. When electronics started showing up, polarity became an issue, due to transistors, diodes, all that solid state magic stuff. In older circuitry (two wire), the white, or common actually went to a building ground. When you reverse that, all your normally neutral lines become hot and potentially very dangerous. Equipment like amps and recievers, and stuff with different voltages internally use the same initial neutral in the circuit. Think of it as a line that you would clip onto if you were on scaffold to keep from falling off. If you put a potential (voltage) on that line, you get bit.

Thanks voodoostation:

It's hard for a person not trained in electricity to understand alot of stuff electricians take for granted. If I understand you, the older devices...when plugged in upside down...actually had circuits that were "lifted" and could run in both directions...is that describing it right??? But I didn't think an electron tube could run backwards??? Wouldn't the tube just shut down???

voodoostation
July 20th, 2008, 03:49 PM
Unless you're still living in 1976 or just like using ancient crap, every piece of modern electrical equipment sold in the U.S. with a real UL rating has a polarized plug, though I honestly think if we quit using polarized plugs we could maybe thin the herd and reduce the number of retreads promoting the use of two prong non polarized plugs. Just a thought.

JKjr
July 20th, 2008, 03:52 PM
Every Sunday morning I lay in the bathtub and make toast and jelly. It's OK though, my toaster has a 3 prong, and I can wash all the dishes without even getting up.

teleman65
July 20th, 2008, 03:54 PM
My tech will not service any gear with 2 prongs unless part of the service includes installing a 3 prong. I've had some nasty shocks and think I'll go with the 3 prong.

Tim Armstrong
July 20th, 2008, 04:08 PM
...there are techs out there that do not like to use them 3 prong plugs on amps for what ever the reason. I know one and woozy at the gear page knows one I would suspect there are certainly more out there. These folks also have been in business for a long time and are not afraid of giving this advice or worried about law suits so who is right and who is wrong hard to say as this is one of those continual debate issues. Jim

I'm pretty sure that you'll find one or two people in ANY field who hold an opinion that's different from the other 99% of their professional peers.

In the case of electronics, they're wrong, and their advice can kill you.

Cheers, Tim

fakeocaster
July 20th, 2008, 06:36 PM
I'm pretty sure that you'll find one or two people in ANY field who hold an opinion that's different from the other 99% of their professional peers.

In the case of electronics, they're wrong, and their advice can kill you.

Cheers, Tim



+1

The laws governing free speech means theyre entitled to say what they like. The laws of physics mean theyre wrong

RodeoTex
July 20th, 2008, 07:00 PM
My tech will not service any gear with 2 prongs unless part of the service includes installing a 3 prong. I've had some nasty shocks and think I'll go with the 3 prong.

Good for your tech, and you too.

With the old unpolarized plugs the chassis of the device or appliance was often 'hot' because the plug was in USD. Back in those days no one even noticed it much because they were standing on a wooden floor and not touching any real earth ground unless they leaned over and touched the sink or something.
I'm am electrician and cannot stand the sight of those old 2 prong unpolarized plugs. For the benefit of Eric Johnson I might put a 2 prong polarized cord on something but I'd still cringe. Modern structures are wired with true earth reference and I don't see any reason not to use it, especially with something that you are holding in your hands and sweating on.

I love the earlier story about paying the bass player to touch his mic and strings to test for a shock for a beer. That sounds like a true road story except my experience says that the drummer would have done it on a dare (every time) for nothing.

surfoverb
July 21st, 2008, 10:37 AM
No offense, but just because Eric Johnson does something is not a license for you to do it to.

Never said it was...I was just responding to someone saying they don't know anybody that doesnt prefer 3 prong when clearly there are people.

EJ does it because 2 prongs sound better :roll: This is the same guy that can differentiate tones of variable battery brands.

Tim's diagnosis may very well be accurate.

guitarzan13
July 21st, 2008, 10:48 AM
Eric Johnson is, well, crazy!

Cheers, Tim
Doesn't he also have the paint removed from under the pickguard?? He says that it allows the wood to "breath". He shoulda left it in the tree if he wanted it to breath.... strange dude, he is.

robrohdeszudy
July 21st, 2008, 12:13 PM
I worked an entire career in electrical and electronics and have accrediation in each. I would absolutely never agree with anyone who refuses to install a hard wired ground to a guitar amp chassis.
If the power cable ground is properly installed, it will always be safe to touch the amp, guitar and strings. Period.
How can anyone, in this modern age, imagine a house or any other structure, wired with a "hot" ground?? If that were the case, sure you'd get a shock. I find it impossible to imagine receptacle wiring to be that screwed up. If in doubt, use a receptacle checker first. 2 wire power cords for guitar amps are archaic and dangerous. Do NOT bet your life on a 2 wire power cord.

BTW a 220k resistor in parallel with a .001 capacitor in the guitar is a "work around" and doesn't address the principle problem. I recommend leaving the instrument(s) as is and ensuring the amp is safe to touch.


+1!! More like +10, since I have most certainly played in venues with incorrect wiring. Sometimes reversed polarity, but very often no real ground. Definitely get a tester. --Rob

robrohdeszudy
July 21st, 2008, 12:17 PM
Would you happen to know why?

Eric Johnson is the same guy who is positively convinced he can hear the difference if the guitar's cord is turned around and plugged in the other way.

Right. That's what I said too.

Not to bash the guy, but he's plainly delusional. I think he needs to be medicated. Hopefully before he gets electrocuted.
--Rob

robrohdeszudy
July 21st, 2008, 12:18 PM
I'm pretty sure that you'll find one or two people in ANY field who hold an opinion that's different from the other 99% of their professional peers.

In the case of electronics, they're wrong, and their advice can kill you.

Cheers, Tim

Well put, Tim. --Rob

Radspin
July 21st, 2008, 02:18 PM
My tech will always install a three-prong plug when repairing a vintage amp. If the customer insists on a two-prong, the tech makes him sign a waiver that the tech is not responsible if something shocking happens.

I have three-prong plugs in all my amps. I've been shocked one too many times while playing live (not recently though).

DickensCPA
July 22nd, 2008, 10:24 AM
I NEVER take anything electrical for granted. Certain additional precautions may not be foolproof, but I at least do everything possible to try and prevent disaster.

I got my degree and took the CPA, but my Dad has been an electric/plumbing contractor for 41 years. As a small child I was "free" labor. He made me get my elec and plumbing license as "something to fall back on." Glad he did. My brother will take over his business and I still take on the odd job with my brother for extra guitar money.

It's pretty common today that white is neutral, black is hot and bare is ground. It wasn't so long ago that it was up to the particular electrician whether he made black OR white hot. Either will work, just be consistent. Still a LOT of buildings out there with white as the hot wire. Imagine a club owner of an older building decides he wants to add an outlet himself. Reads a book and wires it as black=hot. Runs a feed line to the box, pays no attention to all the black wires on ground bar and runs his black into the breaker and his white and ground to ground bar. I went into that long boring piece just as an example of why to never take electricity for granted.

On the flip side, if you have a 3 prong plug and your outlets in an older home are only two prong, it's an easy fix. Buy a 3 prong recepticle and pick up some scrap wire. Usually bedrooms, living rooms, dens and so forth are 14g and kitchen, dining room, bathroom, garage and outside are 12g. 14g plug circuits will be in a 15A breaker and 12g in a 20A breaker. Take a scrap piece of white and hook to the green ground screw on new plug and the other end around the silver colored screws on the side. Silver colored side is neutral and polished brass is hot. Hook your existing wires in the wall to the appropriate hot and neutral side. You've essentially completed the same circuit in an older home with out a ground run.

JimiBryant
July 22nd, 2008, 10:39 AM
I would go three prong on any rig I planned to gig with - but, having
so many amps, I can't justify replacing power cords on all of 'em so I
make due with what I have and anytime a cord or plug starts to look
like it's ready to crumble then I'll replace it with a new heavy-duty
cord w/3-prong plug.

if one has a vintage amp and feels squishy about altering the cord,
just save the old one and you can change it back if you think you're
going to ever sell the amp.

electrocution happens rarely - regardless, it is not your friend.

of course one nice thing about 2-prong plugs is sometimes one can
get rid of 60-cycle hum by unplugging the amp and turning the plug
the other way round then plugging it back in!

bradpdx
July 22nd, 2008, 11:08 AM
Yea and there are still a lot of things out there that have 2 prong plugs that are not polarized too and they are modern stuff so not every one uses polarized plugs on their products.

That's because many objects don't need them - they are totally isolated from ground and don't care where the ground reference is. Harmless.

Amps are such a different thing. If they were always used in isolation from other electronics, it wouldn't matter so much. The danger of a 2-prong plugs stems from the likely fact that the player will be contacting other grounded or ungrounded electronics while using the amp. It's all relative in that respect.

The urgency is compounded by the fact that we still use ancient technology for passive guitar pickups that more or less requires us to use our bodies as ground planes to reduce noise. When you hold the strings of a stock Tele, your body is directly connected to the ground of the amp, acting as a big salt water pool of conductivity that absorbs ambient radiated electrical noise like a lighting rod. Until we all decide to use something like EMGs, this will continue to be the problem.

I cannot believe any responsible tech would refuse to install a 3-prong cord. Yes, you can make a 2-prong cord work if you are careful and observant - years ago I used to carry an electrician's tester in my pocket while setting up on stage - the risks are too great and utterly unnecessary. A 3-prong cord simply increases the probability that you are in fact PROPERLY grounded in the same way as the gear you are likely to touch.

All of us here who have experienced that fabulous "lip toaster" feeling when contacting a microphone that is 120VAC relative to you, please yell "AAGGGHHH!".

AAGGGHHH!

Wally
July 22nd, 2008, 11:28 AM
+another for the 3-prong. +another for wall outlet testers.
I am also not against 'fusing' the guitar ground with the cap/resistor rig.
Note: with humbuckers in a well shielded compartment, the ground to the strings may not be necessary.

milocj
July 22nd, 2008, 11:40 AM
On the flip side, if you have a 3 prong plug and your outlets in an older home are only two prong, it's an easy fix. Buy a 3 prong recepticle and pick up some scrap wire. Usually bedrooms, living rooms, dens and so forth are 14g and kitchen, dining room, bathroom, garage and outside are 12g. 14g plug circuits will be in a 15A breaker and 12g in a 20A breaker. Take a scrap piece of white and hook to the green ground screw on new plug and the other end around the silver colored screws on the side. Silver colored side is neutral and polished brass is hot. Hook your existing wires in the wall to the appropriate hot and neutral side. You've essentially completed the same circuit in an older home with out a ground run.

This will really work? Most of my living room and bed rooms are still two-prong and the wiring is not easily accessible to add the third wire or to run new Romex. If I just jumper the neutral to the ground prong of the receptacle will it also test correctly using those small plug in circuit testers? I've checked my outlets for polarity but it would be nice if I could actually have them grounded, too.

emu!
July 22nd, 2008, 01:11 PM
This will really work? Most of my living room and bed rooms are still two-prong and the wiring is not easily accessible to add the third wire or to run new Romex. If I just jumper the neutral to the ground prong of the receptacle will it also test correctly using those small plug in circuit testers? I've checked my outlets for polarity but it would be nice if I could actually have them grounded, too.

I am concerned on this one. Because there STILL IS NO EARTH GROUND. The round prong is supposed to be tied directly to an earthing rod outside the home. It will allow you to use a 3 prong plug, but doesn't really allow for the use of the earth gound in case of a circuit failure. Kinda like just sawing off the round prong with a hacksaw and plugging in an old socket.:cry:

DickensCPA
July 22nd, 2008, 01:52 PM
I am concerned on this one. Because there STILL IS NO EARTH GROUND. The round prong is supposed to be tied directly to an earthing rod outside the home. It will allow you to use a 3 prong plug, but doesn't really allow for the use of the earth gound in case of a circuit failure. Kinda like just sawing off the round prong with a hacksaw and plugging in an old socket.:cry:

Not quite exactly. First off you may remove your outlet and see a rolled up or nutted bare ground already in there, I have worked on some old remodel or addition jobs and found that. If not, your neutrals are still connected to the bar in your breaker box. The bar in your breaker box should have a #4 bare connected to an 8' ground rod driven into the ground.

Just because an older house doesn't have three prong outlets doesn't mean it's not grounded. On a newer house the neutral and ground go from two separate points on an outlet to the same point in the breaker box. By adding that jumper, you're just completing that same circuit.

Take a bedroom plug for example. 14-2 w ground wire going to a 15A breaker. Take your plug and wrap your bare ground around the green screw up top. Trim your white wire and put it in one of the holes in the back on the silver screw (neutral) side. Trim your black wire and put it in a hole on the polished brass screw (hot) side. 14g wire easily fits in those holes. I've been able to get 12g to fit rarely, but mostly you're gonna be actually wrapping those around the actual screws. Complete your circuit for that room, this means most all your plugs are going to have two sets of wires in them except the first and last plug. One of these two will be marked feed. I usually mark that stud with a sharpie. I take 14-2 w/ground and run from my feed plug to the breaker box. At the breaker box I run my 14-2 thru a grommet up top and trim and fold my wires neatly. Take my hot black and connect to the 15A breaker. Take my white neutral and bare ground and run to the same bar. That's how you wire a house with 3 prong plugs. Would you agree that plug has an earth ground?

Now if I did everything exactly the same as above, but only used 14-2 and no bare ground in the romex covering and hooked a jumper from a ground screw to a neutral, is that not the same circuit and earth grounded?

Radspin
July 22nd, 2008, 02:29 PM
All of us here who have experienced that fabulous "lip toaster" feeling when contacting a microphone that is 120VAC relative to you, please yell "AAGGGHHH!".

Count me in. It's not something you want to experience.

emu!
July 22nd, 2008, 03:21 PM
If not, your neutrals are still connected to the bar in your breaker box. The bar in your breaker box should have a #4 bare connected to an 8' ground rod driven into the ground.

Just because an older house doesn't have three prong outlets doesn't mean it's not grounded. On a newer house the neutral and ground go from two separate points on an outlet to the same point in the breaker box. By adding that jumper, you're just completing that same circuit.


I guess I thought the NEUTRAL connection was the CENTER TAP of the transformer on the pole outside...and it never got sent to earth ground. Kinda like a PT in a guitar amp.:confused: :oops: I learn something everyday here.

DickensCPA
July 22nd, 2008, 03:41 PM
I guess I thought the NEUTRAL connection was the CENTER TAP of the transformer on the pole outside...and it never got sent to earth ground. Kinda like a PT in a guitar amp.:confused: :oops: I learn something everyday here.

There's where you got me. I can wire just about any residential or commercial building out there, but scared to change tubes in an amp!LOL! Back in the early to mid 70's my Dad still did service calls and would get so mad because people would call him (an electrician) and he'd show up and they'd have a problem with a refridgerator or dryer. He used to always scream, "I'm an electrician, not an appliance man!"

Now I'm handy with a solder iron and can fix most anything. I'll redo and rebuild a Harley all day, soup up my wife's vacuum cleaner. I even ripped all the wiring out of my new bass boat and redid it my way. However, the common theme in all of those is they were all mine and unplugging them or disconnecting batteries made me safe.

milocj
July 22nd, 2008, 09:17 PM
I wasn't questioning you're method of grounding a receptacle as I was amazed at how simple a solution this seemed to be rather than trying to replace all the wire with 14/3 or running a separate ground wire back to the main box.

Would there be any downside (or would it likely be against code) to doing the jumpering trick on a couple of 2-wire outlets that I occasionally like to use at home when not jamming with friends in the grounded basement?

refin
July 22nd, 2008, 09:37 PM
I'm pretty sure that you'll find one or two people in ANY field who hold an opinion that's different from the other 99% of their professional peers.

In the case of electronics, they're wrong, and their advice can kill you.

Cheers, Tim


+1000

red57strat
July 22nd, 2008, 09:38 PM
I have never tried this.. but if you insist.
This is from Customizing your Electric Guitar by Adrian Legg.
Dont know what effect on tone it has.. dont think any.

wire a 220k resistor in parallel with a .001 capacitor (assuming microfarads.. I could be wrong tho). Lift the ground from the strings and put this in series with the bridge and the ground...

Make sense?
If not let me know.. I will be more clear.

That doesn't work on a traditional Telecaster.

jhegel
July 22nd, 2008, 09:39 PM
Would there be any downside (or would it likely be against code) to doing the jumpering trick on a couple of 2-wire outlets that I occasionally like to use at home when not jamming with friends in the grounded basement?

National Electrical Code requires that any three prong receptacle installed on an ungrounded (two wire) circuit be protected with a GFCI device. These outlets are relatively cheap around $6.00 to $9.00 each, and one can protect several other outlets downstream from it.

A properly functioning GFCI device will monitor the current on the "Hot" wire compairing it to the return current on the "neutral" wire. They are set to trip at around 6 to 9 milliamps difference preventing a "fatal" shock.

They are a good thing if you have ungrounded circuits.

Wally
July 22nd, 2008, 09:43 PM
That doesn't work on a traditional Telecaster.


This is an inline fuse on the ground to the strings. It works on any guitar. It is not a noise reduction thing. It is a fuse. It will not prevent a mild shock...a tingle..., but it will blow before the current is strong enough to kill you.

red57strat
July 22nd, 2008, 09:44 PM
I'm pretty sure that you'll find one or two people in ANY field who hold an opinion that's different from the other 99% of their professional peers.

In the case of electronics, they're wrong, and their advice can kill you.

Cheers, Tim

This is absolutely true.

Keep in mind that, a 3-prong plug does not insure your safety. If the outlet has a bad ground, you can still become the ground.

Test every outlet that you plug into then test with a voltage sensor. The voltage sensor will show you if there is potential on your amp's chassis and you guitar strings.

Do this every time you play! I had a ground go bad in an outlet strip and was zapped with a correctly wired amp.

Properly wired gear with a 3-prong grounded plug is still safer than gear with a 2-prong plug anyone who tells you otherwise is giving dangerous advice!

SamBooka
July 22nd, 2008, 09:50 PM
That doesn't work on a traditional Telecaster.

I shouldnt admit this in the forum but.. when i see it in my minds eye I think "Strat Vibrato"
My Tele has 3 wires from the bridge pickup.. hot and cold (or +/-.. you know what i mean) and a ground for the copper plate on the bottom.
Wouldnt putting the resistor/cap in series between the copper plate and the ground work?

DickensCPA
July 22nd, 2008, 10:46 PM
I wasn't questioning you're method of grounding a receptacle as I was amazed at how simple a solution this seemed to be rather than trying to replace all the wire with 14/3 or running a separate ground wire back to the main box.

Would there be any downside (or would it likely be against code) to doing the jumpering trick on a couple of 2-wire outlets that I occasionally like to use at home when not jamming with friends in the grounded basement?

I'm sorry, I skimmed right over your question and started conversing with emu. I didn't think you were questioning my method and I hope I didn't come off like a rear end. I meant to answer both of you. I was at the office at the time and you know how it is when you try to work and play at the same time.

It is pretty simple when you think about it. I bought my first house at 22 years old, as you can imagine, it wasn't a mansion. It was built in 1947. The first thing I did was rip out the fuse box and replaced it with a breaker box. About every other time I ran the dryer a fuse shattered with glass everywhere. I changed all my 2 prongs to three in that house.

First things first though, you need to shut off your main in your box before doing anything. You can shut off the individual breaker, but if you choose wrong, zap. You don't want to buy any 14-3 w/ground, that's for light switches, ceiling fans and smoke detectors. It has an extra hot wire (red) for switch legs, ceiling fans with light kit, etc. Check the breaker on the circuit you're going do this on, if it's a 20A, you need 12g wire. 15A you can use 14g.

A GFI plug is similar to a regular plug silver screws are neutral and polished brass are hot. If you have two sets of wires in your gain box then one set is hot and the other is a circuit leg. You'll need to ohm them out because a GFI has a line and a load and you need put them in the right slot. If there's only one set, they're hot.

If I had to guess, they should have wired your basement with 12g, they would now, but I don't know how old your house is. If you went to a construction site and told the electrician you needed about 12-16" of 12g neutral and what you were doing, he would probably give you a piece.

IF you feel UNCOMFORTABLE at all, don't fool with it and risk your life. Like someone earlier mentioned, I might take things I know for granted. I might work on a switch or plug and not even flip the breaker, but I know what I can touch and what I can't. I don;t have that in my knowledge base for a tube amp, so I stay out of it.

Don't know where you're located, but if it's near middle TN, I'll come do it for you. I'd even supply the wire.

mofugly13
July 22nd, 2008, 11:23 PM
National Electrical Code requires that any three prong receptacle installed on an ungrounded (two wire) circuit be protected with a GFCI device. These outlets are relatively cheap around $6.00 to $9.00 each, and one can protect several other outlets downstream from it.

A properly functioning GFCI device will monitor the current on the "Hot" wire compairing it to the return current on the "neutral" wire. They are set to trip at around 6 to 9 milliamps difference preventing a "fatal" shock.

They are a good thing if you have ungrounded circuits.

+10,000

True. You cannot, by code, replace an ungrounded two-prong receptacle with a regular three-prong (grounded) receptacle. You must install a GFCI protected receptacle instead. If you do rig a three prong as was described by jumpng the neutral to the ground screw, and your house ends up burning down, and the insurance investigators find that you did this, you might be SOL as far as insurance is concerned. The neutral wire, while it is grounded at the panel, is a current-carrying conductor, and should NOT be used as a ground. Because it is a current carrying conductor, and part of the electrical circuit, you CAN get a shock from it. The ground wire, when present, is NOT part of the circuit, it is there to protect personnel and equipment, in the event of any stray voltage, or an open neutral. It will, hopefully, carry any stray current directly to earth. Don't jumper your neutral to ground, spend a few bux and buy a GFCI receptacle, it's safer and LEGAL.

milocj
July 23rd, 2008, 11:48 AM
I love the things that can be learned on these forums and that people are so willing to help others.

Let's go back to safe, legal, and simple real quick for my situation. I guess I knew that a GFCI could protect outlets downstream since my old house had a GFCI breaker in the box for the kitchen and bathroom but that still had two-pronged outlets. Am I correct in understanding you guys in that I can install a GFCI outlet in any box in one of my rooms, even if it has the old two-wire romex to it, and that outlet will be properly protected? I guess due to the old house having GFCI breakers I assumed that the first GFCI still had to be wired with the three-wire cable and properly grounded.

If all it takes is a GFCI receptacle in place of an old two-prong I have no problems going that route and can easily do that myself. Is there an easy way to determine which outlets are "downstream" of the GFCI, especially before I choose where to place it? I'm assuming that I should be able to test them after the installation with my little outlet tester (with the GFCI test button) but can I determine this before hand? Most of my wiring is hidden and I can't easily trace the circuits from the basement into individual rooms to see which outlet might be first in the chain.

Would a GFCI installed onto two-wire cable test as being properly grounded with an outlet tester and would any of the three-prong outlets after that one also test as being properly grounded?

Thanks.

red57strat
July 23rd, 2008, 12:29 PM
This is an inline fuse on the ground to the strings. It works on any guitar. It is not a noise reduction thing. It is a fuse. It will not prevent a mild shock...a tingle..., but it will blow before the current is strong enough to kill you.

A traditional Tele makes it's ground to the strings through the bridge pickup base plate, to the pickup height screws, to the bridge and the strings.

I suppose you could interupt the ground between the bridge pickup and its base plate. You could do the same thing to the neck pickup and it's cover. The wiring would be on the pickups themselves.

Not a bad idea, really.

Keep in mind that the volume and tone knobs and control plate will still always be straight to ground unless you use pots with plastic shafts (or plastic knobs) and find a way to insulate the control plate from the pots and switch.

red57strat
July 23rd, 2008, 12:42 PM
Wouldnt putting the resistor/cap in series between the copper plate and the ground work?

Only if you cut the short wire between the pickup's black lead an the plate.

As I stated above, your control plate, knobs and neck pickup's cover is still straight to ground.

Joe M
July 23rd, 2008, 01:28 PM
My tech will always install a three-prong plug when repairing a vintage amp. If the customer insists on a two-prong, the tech makes him sign a waiver that the tech is not responsible if something shocking happens.

My guy won't even look at an amp with a two prong plug unless he changes it to three prong. If you say no, he says to take the amp somewhere else.

Paul in Colorado
July 23rd, 2008, 01:42 PM
I used to have a Super Reverb with a two prong cord. I hooked it up to an SPX 90 effects unit and ran the right channel out to a Deluxe Reverb with a grounded outlet. At one point I touched the SPX 90 and the SR, got a shock and the SPX 90 quit working. After a $130 repair bill from Yamaha, the Super got a three prong power cord.

A few years ago I bought a Bandmaster Reverb head. I tried it out to see if it worked, bought it, brought it home and cut off the two prong end until I could take it to the tech to have it serviced, that service included a three prong power cable.

I have a '63 Gibson Falcon. I won't even plug it in until it get's new caps and other services as above.

I think you can see a pattern here.

Wally
July 23rd, 2008, 02:00 PM
A traditional Tele makes it's ground to the strings through the bridge pickup base plate, to the pickup height screws, to the bridge and the strings.

I suppose you could interupt the ground between the bridge pickup and its base plate. You could do the same thing to the neck pickup and it's cover. The wiring would be on the pickups themselves.

Not a bad idea, really.

Keep in mind that the volume and tone knobs and control plate will still always be straight to ground unless you use pots with plastic shafts (or plastic knobs) and find a way to insulate the control plate from the pots and switch.


Right you are, red. I was simply thinking of isolating the strings with the fuse
since our hands are touching those at all times, practically.

jhegel
July 23rd, 2008, 02:11 PM
I love the things that can be learned on these forums and that people are so willing to help others.

Let's go back to safe, legal, and simple real quick for my situation. I guess I knew that a GFCI could protect outlets downstream since my old house had a GFCI breaker in the box for the kitchen and bathroom but that still had two-pronged outlets. Am I correct in understanding you guys in that I can install a GFCI outlet in any box in one of my rooms, even if it has the old two-wire romex to it, and that outlet will be properly protected? I guess due to the old house having GFCI breakers I assumed that the first GFCI still had to be wired with the three-wire cable and properly grounded.

If all it takes is a GFCI receptacle in place of an old two-prong I have no problems going that route and can easily do that myself. Is there an easy way to determine which outlets are "downstream" of the GFCI, especially before I choose where to place it? I'm assuming that I should be able to test them after the installation with my little outlet tester (with the GFCI test button) but can I determine this before hand? Most of my wiring is hidden and I can't easily trace the circuits from the basement into individual rooms to see which outlet might be first in the chain.

Would a GFCI installed onto two-wire cable test as being properly grounded with an outlet tester and would any of the three-prong outlets after that one also test as being properly grounded?

Thanks.

Yes you can install a GFCI outlet in place of a two wire/prong outlet anywhere in the house. The absence of the ground wire will not inhibit the function of the GFCI.

Turn off the breaker for the circuit you are working on and go around with your tester to check which outlets are on that breaker. The one closest to the panel is most likely the first outlet in the chain. Determine which wires are the 'line' and which are the 'load', and install the GFCI outlet accordingly. You can then reenergize the circuit and check with your tester to make sure the downstream outlets are GFCI protected.

Your tester will still show an open or missing ground.

While the GFCI provides a measure of protection, it does not completely replace the equipment grounding conductor.

59TweedVibrolux
July 27th, 2008, 08:25 AM
Probably for the same reason that he labels all of his patch cables so they always go the same way, because he hears a difference (or at least THINKS he hears a difference). He's kinda legendary for his rather extreme fixation on the very tiniest possible variables....

Like I said, he's crazy!

:mrgreen:

Cheers, Tim

This is man that takes the screw out of his Fuzz Face and replaces it
with a Rubber Band to hold the bottom on..... Cause it Sounds Better.
:shock: I took all the screws outa my pedals, wrapped a rubber band
round em....couldn't hear any difference :lol: ...Guess I don't hear what
Eric hears :roll: Best Tone I ever heard him get was a '57 Strat straight
into an Amp, No Reverb, No Delay, No Effects !!!

ramseybella
August 1st, 2008, 12:58 PM
Eric Johnson converts his amps (twins) to 2 prong if they're not already.


I don't think Steve Irwin thought a Sting Ray would end his life as well?
BS install that three prong plug.

Tritone
February 28th, 2010, 03:42 AM
I live in China and bought a Roland Cube 30x locally which has only a 2 pronged plug. From what I'm reading, this is pretty dangerous, right? But honestly I don't trust any electricians in this country, I'll probably just buy a new amp if it's that dangerous.

Donnie55
February 28th, 2010, 09:12 AM
I dont know I kinda like a good 120 jolt first thing in the morning gets my day going........:lol:

brookdalebill
February 28th, 2010, 09:19 AM
Danger, Will Robinson Danger!

Fearnot
February 28th, 2010, 11:29 AM
I've had a couple shocks where all I saw was white for a second or two. I like 3-prongs.

Robster
February 28th, 2010, 11:59 AM
Most of the old 2 prong plugs and wire are in pretty bad shape now after 40 or 50 years with scraped off insulation, loose wires inside. I always save the old cords with all old parts I remove from an amp and the 3 wire mod is easy to remove anyway. Most of the old cords on some amps are too short anyway. I always put a nice 12 foot cord on my amps I repair.

backalleyblues
February 28th, 2010, 01:53 PM
I dont know I kinda like a good 120 jolt first thing in the morning gets my day going........:lol:

Is that why your hair is curly?!?!?!?!

:lol:

Franc Robert

peteb
February 28th, 2010, 02:24 PM
I have no experience with Roland amps.

"From what I'm reading, this is pretty dangerous, right?"



I have played thru one old 2 prong amp or another mostly everyday for the last 10 years.

The shocks I have recieved have all been small.


I have not been shocked for many years, ever since I figured out how to plug the amp in the 'right' way.


Be careful, I have no experience with Roland amps

pbenn
February 28th, 2010, 04:28 PM
Post Of the Year nomination....

E5RSY
February 28th, 2010, 06:45 PM
I don't think Steve Irwin thought a Sting Ray would end his life as well?

That's why I'm selling mine:

http://www.bassemporium.com/item.php?sku=B002920

Jupiter
September 11th, 2010, 04:11 AM
I live in Japan, where the outlets are ALL two-prong. They're polarized; that is, the left slot is bigger than the right one, so that with some appliances you can only plug it in one way, but most power cords don't even have polarized plugs.

Thing is, I bought a Tweaker amp head from the States (long story), and of course it comes with a 3-prong cord. It's one of those standardized detachable power cords, like you find on some computers and such. In fact, my iMac power cord fits the same receptacle on the head.:smile: That iMac cord has the separate ground wire sprouting out of the plug, but none of my sockets have anything to attach it to....

I've read through this whole thread, and understood about 75% of it ("Three prongs good; 2 prongs bad"), but I'm still wondering about my specific case. The whole country of Japan is 2-prong--amps, hairdryers, refrigerators, etc. Why haven't I or anyone in my family ever been shocked? If I get a 3-to-2 adapter/ground lifter plug that's also polarized, will I be okay in the Land of the Polarized Outlet? Assuming that I don't want to re-wire my entire house and anyplace else where I play or modify my guitars, what do I have to do to be safe?

teleamp
September 11th, 2010, 06:50 AM
I totally agree that a 3 prong plug is a safety necessity.

Not knowing alot about electricity, I am still confused on how an electrical device could EVEN WORK properly when a 2 blade plug is turned "upside down"???? I mean...on a standard wall outlet, one blade is HOT...one blade is NEUTRAL, and the round prong is EARTH GROUND...right??? Flipping the plug upside down will feed the electrical device a nuetral signal when it is expecting a hot AC signal...right??? The device shouldn't even work at all if logic applies. What am I missing???

:confused: :confused:

Reversed polarity.

In the old days if the fridge bit you, turn the plug!

teleamp
September 11th, 2010, 06:52 AM
No matter how safe your amp/power cord is, it has no effect if the receptacle is not wired correctly.

teleamp
September 11th, 2010, 07:00 AM
I live in Japan, where the outlets are ALL two-prong. They're polarized; that is, the left slot is bigger than the right one, so that with some appliances you can only plug it in one way, but most power cords don't even have polarized plugs.

Thing is, I bought a Tweaker amp head from the States (long story), and of course it comes with a 3-prong cord. It's one of those standardized detachable power cords, like you find on some computers and such. In fact, my iMac power cord fits the same receptacle on the head.:smile: That iMac cord has the separate ground wire sprouting out of the plug, but none of my sockets have anything to attach it to....

I've read through this whole thread, and understood about 75% of it ("Three prongs good; 2 prongs bad"), but I'm still wondering about my specific case. The whole country of Japan is 2-prong--amps, hairdryers, refrigerators, etc. Why haven't I or anyone in my family ever been shocked? If I get a 3-to-2 adapter/ground lifter plug that's also polarized, will I be okay in the Land of the Polarized Outlet? Assuming that I don't want to re-wire my entire house and anyplace else where I play or modify my guitars, what do I have to do to be safe?


This!

This is why I personally have nothing against a non polarized 2 prong power cord. I grew up in an old house with polarized receptacles... you learn how to plug things in properly.

Here in the states everyone relies on someone else for their safety nowadays.

Jupiter
September 11th, 2010, 07:34 AM
This!

This is why I personally have nothing against a non polarized 2 prong power cord. I grew up in an old house with polarized receptacles... you learn how to plug things in properly.

Here in the states everyone relies on someone else for their safety nowadays.

Thanks for the "This!", but it really wasn't a rhetorical question.:smile:

I really do want to know: Will I be okay with my amp on a 2-prong cord as long as as it's plugged the "right way" into a polarized outlet? Do I have to make sure that EVERYTHING I touch while holding my guitar (like my multi-effects pedal, mic, etc.) is also plugged in the same way?

Mark F
September 11th, 2010, 07:40 AM
The whole country of Japan is 2-prong--amps, hairdryers, refrigerators, etc. Why haven't I or anyone in my family ever been shocked? If I get a 3-to-2 adapter/ground lifter plug that's also polarized, will I be okay in the Land of the Polarized Outlet? Assuming that I don't want to re-wire my entire house and anyplace else where I play or modify my guitars, what do I have to do to be safe?

I'd imagine in Japan, electrical appliances are double insulated, whereby electrical components are encased in insulating material, so in the case of a short in the electrical components, no part of the appliance that can be handled will become live. It relies heavily on quality control on the part of manufacturers.

Also, most buildings in Japan have no real earth electrode. It's less expensive to double insulate appliances than to overhaul the electrical system used in the whole country (though they could 'phase' grounding in if they thought it necessary)

Jupiter
September 11th, 2010, 08:09 AM
I'd imagine in Japan, electrical appliances are double insulated, whereby electrical components are encased in insulating material, so in the case of a short in the electrical components, no part of the appliance that can be handled will become live. It relies heavily on quality control on the part of manufacturers.

Hmm, maybe, but I wonder. Practically everything in Japan is made in China nowadays, just like everyplace else. That goes for my amp head too, of course. . . .:neutral:

I guess an amp really could not practically be made like that anyway, though, could it?

SoK66
September 11th, 2010, 09:54 AM
Now my amp tech as many here know as I posted a reference to this before does not believe in changeing them over either. He said you plug in your amp and listen to it then reverse the plug and plug it in and listen to it again. which ever way is quieter is the proper way for that wireing of the place your in.

Oh, sure, you can get rid of the buzz, but your tech has obviously never had the pleasure of having a 6 inch blue spark jump from an unpolarized house system mic to his lip and being knocked off his feet and onto his butt in front of 10,000 fans. Having had this, and numerous other "shocking" experiences using two-prong amps with their glorious death caps & ground switches, I can assure you anyone (including Eric Johnson) who espouses retaining them is a bloody idiot. If someone is worried about "vintage value" that much that they want to disregard their own safety, fine, but don't plug the amp in and use it. Heavens....

tap4154
September 11th, 2010, 10:05 AM
Doesn't he also have the paint removed from under the pickguard?? He says that it allows the wood to "breath". He shoulda left it in the tree if he wanted it to breath.... strange dude, he is.

EJ is OCD.

NO reason not to put a grounded cord on an old amp. My Champ also has less hum now, and actually sounds clearer IMO. Any tech that refuses to put a 3-prong cord on is a "tech" I'd avoid. Who knows what other shady or "superstitious" practices he may apply to the interior components?

teleamp
September 11th, 2010, 10:41 AM
...? Do I have to make sure that EVERYTHING I touch while holding my guitar (like my multi-effects pedal, mic, etc.) is also plugged in the same way?

That is a very valid question!

And on such a serious concern I will let someone more qualified than myself answer that.

People here in the states assume that if the receptacle has 3 holes it's safe... USE A TESTER, even if your amp has a properly wired cord it doesn't mean ***** if you plug into a faulty outlet!

celeste
September 11th, 2010, 10:42 AM
Current two wire devices are required to be double insulated, that is there at least two layers of insulation between a current carrying conductor and a person at all times, to get UL rating. You could do it with a guitar amp, but it would require something like a isolation transformer on the input, and that gets expensive fast

tap4154
September 11th, 2010, 10:52 AM
Of course the outlet could still have the neutral and hot wires switched, or elsewhere in the building as well. But if you have a 3-prong cord (and the outlet is sctually grounded... I've seen 3-prong outlets installed with no ground wire attached, and the box was isolated as well), at least you aren't the only path for electricity to travel to ground if your strings have voltage going to them, and you touch grounded metal like a mic or faucet etc.

telex76
September 11th, 2010, 10:57 AM
yeah its a shame all the guitar players from the 50's and 60's were electrocuted. There might have been some good music.

tap4154
September 11th, 2010, 11:13 AM
Hey, was was shocked all the time in the 70's by my Champ Amp. Fortunately, I was never grounded, just stung by the strings a bit, so I didn't die, and wasn't a good player anyway.... so.

But IMO it's just dumb not to update your vintage amp. Not just for safety, but for less hum.

No laws against being dumb in America, so feel free to keep them stock ;o)

Birdmankustomz
September 11th, 2010, 11:37 AM
The idiot I bought my 60 watt tube head from ripped the ground prong out of the plug. I'm thinking I'll just put in a socket so I can use removable cords in the future.

jefrs
September 11th, 2010, 11:52 AM
I live in China and bought a Roland Cube 30x locally which has only a 2 pronged plug. From what I'm reading, this is pretty dangerous, right? But honestly I don't trust any electricians in this country, I'll probably just buy a new amp if it's that dangerous.

The Roland CubeNNX are 'double-insulated' (concentric box symbol) plus they are solid-state (low voltage) which allegedly makes them safe. Not!

Double-Earthed only applies to equipment where you cannot touch the chassis. The CubeNNX chassis can be touched, it is the outer of the input jack i.e. your guitar strings, and the top/back panel is metal. The concentric box (to the RHS of "Roland" on the rear model label) marking is in error and a matter for the trading standards safety people.

Once you have had a shock from an amp, you will never, never, never use an old 2-pin one or one without an earth. I also recommend using an RCD circuit-breaker on all systems at all times, it can kill the power before it kills you.

It may not be the amp that goes wrong but other equipment but you want to dump charge through an appliance, not you.

I got a 3-wire fitted to my Cube20X, plus the chassis earthed (and it's quieter too).
This is very easy to do with some pukka 3-conductor mains flex on your country's 3-pin plug, two spade connectors and an earth eyelet tag-washer.

tap4154
September 11th, 2010, 12:12 PM
Now if I did everything exactly the same as above, but only used 14-2 and no bare ground in the romex covering and hooked a jumper from a ground screw to a neutral, is that not the same circuit and earth grounded?


This is actually more dangerous than leaving it non-grounded. It's called a "false ground".

Info
http://www.inspectapedia.com/electric/False_Grounding.htm

Mark F
September 11th, 2010, 12:17 PM
Thanks for the "This!", but it really wasn't a rhetorical question.:smile:

I really do want to know: Will I be okay with my amp on a 2-prong cord as long as as it's plugged the "right way" into a polarized outlet? Do I have to make sure that EVERYTHING I touch while holding my guitar (like my multi-effects pedal, mic, etc.) is also plugged in the same way?

Missed this Jupiter, sorry...

You will be much better off making sure your amp is plugged in 'the right way', and also making sure everything is plugged in 'the right way' that's in your chain.

Just wondering, do the plugs over there have fuses inside?

Agave_Blue
September 11th, 2010, 12:45 PM
Found on another forum, but probably worth repeating here:

With more folks discovering the joys of a tube amp. and some finding a little bundle of tube joy at garage sales, pawn shops etc., It's essential to know that older amps that have a two prong power cord, can be quite dangerous. Even those that have been fitted with a 3 prong power cord, that came with a 2 prong cord in it's original state, may not be wired to modern standards correctly.

Most tube amp folks know this, but some may not. Hence this post.

I'm no expert on which amps had this configuration, but most older Fenders do, and I'm sure many others.

For those that have an older amp. it would be wise to check out the power wire circuit, or if you're not used to working inside an amp, have an amp tech do it for you.

Referring to the illustration below, you can see that if the death cap fails, and they all do at some point, then the power shorts to ground, ( Chassis), and guess where the ground path lies? Through your guitar cord, through your strings, and then through you!

This is not meant to scare folks away from a sweet old amp, but to make some folks aware that a possible hazard exists.

I'm sure that some of the hard core amp guys here will chime in and offer more info, but amp makers were more concerned with protecting the amp in times past, than protecting the player!

So buy that old amp. Play it like you stole it, but know what you have, and be safe with it.

http://i1023.photobucket.com/albums/af351/mikei182/50-60-f4.gif

Cheers! :thumb:

Worth repeating: Just because your vintage amp has a 3-prong cable, doesn't mean it's wired safely!

And: There is no good reason, outside of museum pieces, to leave the original wiring scheme in place. If the amp gets used, the power supply should be rewired. In my opinion. :laugh2:

Here's a nice graphic layout of the Fender circuit, along with simple instructions that even my puny mind could follow: Install - 3 Prong Power Cord on a Vintage Fender Amp | Guitar Files(TM) (http://www.theguitarfiles.com/guitarfile644.html)

I was even able to reuse the original wiring, and had a nice piece left over after the conversion, too! :D

http://www.mylespaul.com/gallery/data/723/medium/trainingday_001.JPG

http://www.mylespaul.com/forums/squawk-box/103068-death-cap-2-prong-power-cords-caution.html

Jupiter
September 11th, 2010, 05:57 PM
Just wondering, do the plugs over there have fuses inside?

I don't think so, but I don't really know what a plug with a fuse would look like; the plugs here look exactly the same to me as (2 prong) plugs in the US, and I've never had one cook off, so I'm guessing not.

Guitar_Ninja
September 11th, 2010, 06:54 PM
Any large appliance or device in Japan which requires a ground will have a special plug connected to it with a copper plate on the bottom which then fits into a special grounded outlet. You screw it down into the outlet and voila, there's your ground. Everything else is double insulated.

Most newer homes there should have these special outlets installed in say the kitchen for the fridge, the living room for the air conditioner, etc. If not then you need to get one installed.

Does seem odd not to have a ground plug, seeing as how the voltage there is only 100V. Much higher current running through those lines than Europe, or even North America.

As far as amps go, nothing is safer than keeping the chassis at ground potential.

Mark F
September 11th, 2010, 07:06 PM
I don't think so, but I don't really know what a plug with a fuse would look like; the plugs here look exactly the same to me as (2 prong) plugs in the US, and I've never had one cook off, so I'm guessing not.

If there is no fuse in the plug, your relying on the breaker/fuse at the board.

If you can, i'd definately get a grounded socket installed (as Ninja says)

And definately check everything is plugged in the right way until then

fly135
September 11th, 2010, 09:04 PM
Also, most buildings in Japan have no real earth electrode. It's less expensive to double insulate appliances than to overhaul the electrical system used in the whole country (though they could 'phase' grounding in if they thought it necessary)if they don't tie either side to ground then the person won't be grounded.

Mark F
September 11th, 2010, 09:18 PM
if they don't tie either side to ground then the person won't be grounded.

there are circumstances where the person could be at a different potential to the live, all depends on things like where someones playing, the building structure, or anything they touch with guitar in hand. If the polarity is kept correct, there probably wouldn't be a problem, but there's a reason most countries have moved over to having earthing systems. Japan has gone in a different direction, and as i've said, without knowing the ins and outs i'd at least recommend keeping correct polarity, with a possibility of having a grounded socket fitted (which seems to be happening slowly in Japan given other posts). That's just me though...

DenisS
September 12th, 2010, 11:17 AM
A 3-prong A.C. cable gets added to every old Fender I work on.

But then other things are necessary.

1 - Resequence the power path to put the switch ahead of the fuse so that when you replace the fuse you are not dealing with a live fuse-holder.

2 - Make the neutral go directly to the power transformer (to the white if you have one on your transformer). Also to the courtesy outlet silver screw.

3 - Add a center-off polarity switch with a safety cap to chassis, so that if the wall outlet is wired wrong you can take your polarity switch out of the center position and set it to the side that gives less hum when you buzz the amp through your guitar cable with your hand at low volume.

Now you have a hard ground, and if the wall is wired wrong you have a cap-coupled neutral to chassis like an old amp that is plugged-in correctly.

The safety cap is good, but the standard old cap will work fine. Safety caps fail by opening-up instead of shorting out. That may rarely happen, but it's safety.

Scotty 2
September 12th, 2010, 12:49 PM
Eric Johnson is the same guy who is positively convinced he can hear the difference if the guitar's cord is turned around and plugged in the other way.

Right. That's what I said too.

Not to bash the guy, but he's plainly delusional. I think he needs to be medicated. Hopefully before he gets electrocuted.
--Rob
Can Eric also tell a differance in tone when
right hand vrs,left hand playing guitar? That's splittin them
straws pretty fine,isn't it?:shock:

Tele-Champ
September 12th, 2010, 02:04 PM
All of us here who have experienced that fabulous "lip toaster" feeling when contacting a microphone that is 120VAC relative to you, please yell "AAGGGHHH!".

Count me in. It's not something you want to experience.


+1. Not fun. Have had it happen once or twice to me. Kind of ruins a jam.

rainedave
September 13th, 2010, 11:57 PM
From a 1950's Fender amp manual:

"If when the amplifier is first turned on one experiences a slight hum more commonly known as line noise and if the amplifier pops or crackles when the metal parts or strings of the instrument are touched, it is an indication that the A.C. plug is improperly polarized; to rectify this condition, it is only necessary to remove the 110 volt A.C. plug from the socket, rotate one-half turn, and re-insert the plug. The amplifier is then properly grounded and will cause no more difficulty."

jh45gun
September 14th, 2010, 12:19 AM
From a 1950's Fender amp manual:

"If when the amplifier is first turned on one experiences a slight hum more commonly known as line noise and if the amplifier pops or crackles when the metal parts or strings of the instrument are touched, it is an indication that the A.C. plug is improperly polarized; to rectify this condition, it is only necessary to remove the 110 volt A.C. plug from the socket, rotate one-half turn, and re-insert the plug. The amplifier is then properly grounded and will cause no more difficulty."


Which is what my tech believes in. I figure you can always put a voltage meter on the chassis and the mic stand to make absolutely sure.

telex76 yeah its a shame all the guitar players from the 50's and 60's were electrocuted. There might have been some good music.


Yea I been shocked more than a time or two but nothing major. I always just checked the plug for the proper polarity and made sure the PA was plugged in the same way.

Though most of my stuff all has three prong plugs now you still can use a two prong if you know what your doing and you check the circuits of the places you play with a circuit tester.

65flh5326
September 14th, 2010, 12:45 AM
"A 3-prong A.C. cable gets added to every old Fender I work on."

Well you aint working on my old Fender amps!

"Though most of my stuff all has three prong plugs now you still can use a two prong if you know what your doing and you check the circuits of the places you play with a circuit tester."

A voice of reason?

Maybe I am getting sick and tired of arm chair heroes trying to save me from myself!

tap4154
September 14th, 2010, 10:18 AM
From a 1950's Fender amp manual:

"If when the amplifier is first turned on one experiences a slight hum more commonly known as line noise and if the amplifier pops or crackles when the metal parts or strings of the instrument are touched, it is an indication that the A.C. plug is improperly polarized; to rectify this condition, it is only necessary to remove the 110 volt A.C. plug from the socket, rotate one-half turn, and re-insert the plug. The amplifier is then properly grounded and will cause no more difficulty."

Hey, in 1950 even doctors endorsed smoking cigarettes on TV and in print ads. We learn and adapt all the time. But if folks want to live in the past out of some superstition that not having a properly-grounded amp will improve their tone, that's fine by me. I frankly don't care if you buckle your seatbelt either, if you think it makes you drive better ;o)

DenisS
September 14th, 2010, 11:59 AM
"A 3-prong A.C. cable gets added to every old Fender I work on."

Well you aint working on my old Fender amps!

"Though most of my stuff all has three prong plugs now you still can use a two prong if you know what your doing and you check the circuits of the places you play with a circuit tester."

A voice of reason?

Maybe I am getting sick and tired of arm chair heroes trying to save me from myself!

No you don't see the whole picture. I have been working on Fenders and all else while you were running around in three-corner pants. I am a master electrician and ran McIntosh Service clinics in the '70s. Worked on industrial, medical, scientific and consumer electronics digital, and analog all my life. Transmitters, amps, recievers, CNC machinery, spectralanalysers, whatever. If you get any packages through UPS from the Northeast, they were handled by motor controls that I designed and installed. I do all these things as a living every day.

Your "armchair" comment is presumptuous. Benefit of the doubt: won't call it ignorant, but you are forcing me to blow my own horn, and I don't like that.

Also there is a liability issue for a professional tech like myself. I can't have my people in danger of the Kieth Relf syndrom, may he rest in peace.

Do what you want. There is nothing wrong with polarizing your 2-prong by hand every time. It's not the safest way for the general public.

Fender did not do their 3-prong circuit right either at the beginning. Do you even understand why? Can you even follow this simple circuit?

When you go to an open mic with your amp, do you really upset the whole proceedings by buzzing your amp or measuring your chassis in relation to ground? Or are you one of those guys who does not notice that he is playing leads over the vocal? School yard antics.

Are you just in a grumpy mood today, or are you a raving PITA? Don't mess with me son. You got a long way to go.

DenisS.

65flh5326
September 14th, 2010, 12:24 PM
"Are you just in a grumpy mood today, or are you a raving PITA? Don't mess with me son. You got a long way to go."

I know a thing or two about tube electronics, come over to the "practical machinist forum" "Monarch Lathes". tell us how to do it junior.
http://i170.photobucket.com/albums/u265/donsmonarch10ee/moduleEElathe003.jpg

http://i170.photobucket.com/albums/u265/donsmonarch10ee/EEdualvoltage005.jpg

http://i170.photobucket.com/albums/u265/donsmonarch10ee/monarcheeelectricallayout.jpg

DenisS
September 14th, 2010, 12:27 PM
Nice work, son.

If you built that you can come over for dinner and we can fight in-person. :razz:

SoK66
September 14th, 2010, 10:38 PM
Found on another forum, but probably worth repeating here:

Very good point Agave. I've been into a number of "converted" vintage amps, where the tech has just wired in a three prong cord in place of the old two pronger, usually at the courtesey outlet, grounded the green wire and left the ground switch and death cap as is. Bad news. In a number of cases the amps were fused on the neutral line ( white, instead of on the hot line (black). So, you've got unfused hot power going into the amp. Always eliminate the two prong courtesey outlet, death cap & ground switch entirely. Wire black to the center tap on the fuse holder, then to the switch, then to the PT. White goes right to the PT, green to the nearest PT stud. Done. You're polarized, you're safe and your amp will be buzz free. If Eric Johnson objects, send him to a doctor.

BTW, it's reported EJ will not use a vintage amp that's been recapped either.

smokerjoe34
September 14th, 2010, 11:17 PM
What about the little 3 prong adapter that plugs in to the 2 prong cord to make a ground connection ?? Are these cool ??

RodeoTex
September 15th, 2010, 12:09 AM
"Are you just in a grumpy mood today, or are you a raving PITA? Don't mess with me son. You got a long way to go."

I know a thing or two about tube electronics, come over to the "practical machinist forum" "Monarch Lathes". tell us how to do it junior.

Please explain to us all the difference between a grounded conductor and a grounding conductor, then get back to us. Pictures don't prove much of anything in electrical theory, no matter how pretty they are (contactors usually don't appear too much in amps)
.

Edit:
Is Rod W. still there at Key?

markothefish
September 15th, 2010, 07:29 AM
You guys have frightened me into good sense . I will be re wiring a 3 pronged grounded power cable on my old Silvertone Amp this weekend . I've been meaning to get around to it but have always put it off .

http://www.tdpri.com/telephoto/data/500/P1010699.jpg

DenisS
September 15th, 2010, 07:59 AM
Make sure it has a power transformer first. If no then you change your strategy (like an old AA5 radio).

SteveGangi
September 15th, 2010, 12:10 PM
I worked an entire career in electrical and electronics and have accrediation in each. I would absolutely never agree with anyone who refuses to install a hard wired ground to a guitar amp chassis.
If the power cable ground is properly installed, it will always be safe to touch the amp, guitar and strings. Period.
How can anyone, in this modern age, imagine a house or any other structure, wired with a "hot" ground??
Same here. Speaking also as an engineer and a repairman, anyone who says not to make your equipment safer, or who presents himself as a tech and refuses to make your gear safer, should not get your business anymore. He is a fool and you are a fool if you keep going back to him.

I'm pretty sure that you'll find one or two people in ANY field who hold an opinion that's different from the other 99% of their professional peers.

In the case of electronics, they're wrong, and their advice can kill you.

Cheers, Tim
Yes, they are idiots and can get someone killed. I myself have NO patience with that particular brand of stupidity.

Don't count on the "death cap" in a two prong system to protect you. It's a flaky system, it relies on you guessing which way to throw the switch, and if the capacitor fails, there you go. It's called the Death Cap for a reason.

Agave Blue posted the diagram on how to convert to a three prong set up. USE IT. Install the third wire, install the fuse, take out the Death Cap.

Parting shot: A few posts have various nonsensical things attributed to Eric Johnson. I can tell people with a good amount of confidence that no matter what he thinks he can hear, he is full of ****. Guitar cords are not directional. Anyone who claims he can hear which way a cord is connected is a liar. The same goes fort the “stereo experts” who claim they can hear what “direction” the speaker wire (glorified zipcord) is “going”. It’s horse ****. Even worse, removing the ground from equipment is dangerous and can get someone killed. The laws of physics are on my side.

I use strong words on purpose. Listening to fools and liars can get you killed. Go to a good three wire hard ground system and stop risking your lives.

fly135
September 15th, 2010, 12:26 PM
Nice work, son.

If you built that you can come over for dinner and we can fight in-person. :razz:But that begs the question... Why would he have anyone else working on his amp?

rainedave
September 15th, 2010, 12:36 PM
I want to clarify that my posting of the paragraph from old Fender manual was done for historical purposes only.

I support safety 100%. I was not advocating the use of 2-prong cords.

I simply thought it was interesting, in the context of this discussion, to show evidence of archaic approaches on the part of a major amp manufacturer.

DenisS
September 15th, 2010, 03:17 PM
Same here. Speaking also as an engineer and a repairman, anyone who says not to make your equipment safer, or who presents himself as a tech and refuses to make your gear safer, should not get your business anymore. He is a fool and you are a fool if you keep going back to him.


Yes, they are idiots and can get someone killed. I myself have NO patience with that particular brand of stupidity.

Don't count on the "death cap" in a two prong system to protect you. It's a flaky system, it relies on you guessing which way to throw the switch, and if the capacitor fails, there you go. It's called the Death Cap for a reason.

Agave Blue posted the diagram on how to convert to a three prong set up. USE IT. Install the third wire, install the fuse, take out the Death Cap.

Parting shot: A few posts have various nonsensical things attributed to Eric Johnson. I can tell people with a good amount of confidence that no matter what he thinks he can hear, he is full of ****. Guitar cords are not directional. Anyone who claims he can hear which way a cord is connected is a liar. The same goes fort the “stereo experts” who claim they can hear what “direction” the speaker wire (glorified zipcord) is “going”. It’s horse ****. Even worse, removing the ground from equipment is dangerous and can get someone killed. The laws of physics are on my side.

I use strong words on purpose. Listening to fools and liars can get you killed. Go to a good three wire hard ground system and stop risking your lives.

That diagram can lead to problems. The one on the left will give you current through your reference cap if the wall is not wired correctly, and you fail to catch it with your input-buzz polarity test. They have been known to short and rip at the seams from that. This is why an expensive safety cap should be used - its' failure mode is to go open.

The diagram on the right will float the chassis if the wall outlet has no ground or there is a 3 to 2 converter for an old outlet. May be a problem sometimes.

This is why a 3 position center-off polarity switch is used on modern equipment. And why it is good to put one on an old amp (as long as it is not a transformerless jobby). Really this is a combo of both diagrams plus center-off.

In truth no system automatically takes care of all contingencies. The hard ground with 3 position switch comes the closest, but we still need to buzz the amp for polarity switch position if we suspect the wall outlet is wanked.

I'm sure there are proponents of using an isolation transformer, like when we fix old transformerless AA5 radios on the bench. But it would be a big one for our amps. I did install one into an old series-string amp for a guy a few years ago. I don't want my customer dead, he let me do it.

You still want to make sure the mics are not hot in relation to ground, but we never do that untill someone gets their lips burnt off.

Did you ever get that blue ozone flash?

SteveGangi
September 15th, 2010, 03:59 PM
That diagram can lead to problems. The one on the left will give you current through your reference cap if the wall is not wired correctly, and you fail to catch it with your input-buzz polarity test. They have been known to short and rip at the seams from that. This is why an expensive safety cap should be used - its' failure mode is to go open.

The diagram on the right will float the chassis if the wall outlet has no ground or there is a 3 to 2 converter for an old outlet. May be a problem sometimes.

This is why a 3 position center-off polarity switch is used on modern equipment. And why it is good to put one on an old amp (as long as it is not a transformerless jobby). Really this is a combo of both diagrams plus center-off.

In truth no system automatically takes care of all contingencies. The hard ground with 3 position switch comes the closest, but we still need to buzz the amp for polarity switch position if we suspect the wall outlet is wanked.

I'm sure there are proponents of using an isolation transformer, like when we fix old transformerless AA5 radios on the bench. But it would be a big one for our amps. I did install one into an old series-string amp for a guy a few years ago. I don't want my customer dead, he let me do it.

You still want to make sure the mics are not hot in relation to ground, but we never do that untill someone gets their lips burnt off.

Did you ever get that blue ozone flash?
No, my amp has the three wire power cord and a "polarity" switch. When I am not sure of someone else's gear, I check it with a Voltmeter. You are right about the safety capacitor though, I was "obsessing" over the other more obviously wrong stuff being floated.

BigDaddyLH
September 15th, 2010, 04:29 PM
Story time. I lived in the UK in the late '80s, in a shared house. I got tired of burning my morning toast on the oven's eye-level grill
http://www.applianceplanet.co.uk/images/Beko/BC5NEWP.jpg
so I bought a toaster. I brought it home, went to plug it in and WTF?! the electric cord had no plug on its end! My housemates laughed at me -- you have to plug separately, isn't that the way it is in Canada, too? Huh? I asked why, and they just said that's just the way it's always been, which seemed a perfectly good answer to them, but not me. Later, I also saw an advert for a stereo system that listed all its advanced features, including a remote control (which was the bee's knees at the time) as well as a "fitted plug" :lol:

65flh5326
September 15th, 2010, 04:45 PM
All this dribble, "Death Caps" Danger, Danger, Danger!!!!
Complete nonsense!
Search for yourself, not one person killed by a Fender amp can be found.

I found this, very entertaining, the amp was powered up, the guy stuck his finger in it.

http://www.youtube.com/watch?v=1lozkT1zrIU

So, where are all the dead bodies?

Triton Thrasher
September 15th, 2010, 04:54 PM
As we're talking about toasters again, there's a school of thought that says it's safer not to earth them, because so many people hold the case with one hand as they fish around inside with a knife, for stuck bits of toast.

DenisS
September 16th, 2010, 04:23 PM
As we're talking about toasters again, there's a school of thought that says it's safer not to earth them, because so many people hold the case with one hand as they fish around inside with a knife, for stuck bits of toast.

You mean I shouldn't be doing that? How about with a fork then?

BigDaddyLH
September 16th, 2010, 04:37 PM
You mean I shouldn't be doing that? How about with a fork then?

3 prong or 4 prong? :lol:

postjob62
September 16th, 2010, 10:06 PM
Guys, I understand and accept that 3 prong cords are the accepted safety standard today and I don't mean to be contrary-I really don't know jack compared to some of you who do. But I do have to ask: has something happened to the nature of electricity or how wiring is done to increase this danger in the last however-many years? It just seems that players would have been dying left and right back in the day...

Also, is there anything one can do to increase his odds of living with a 2 pronger that he wants to keep stock for historical/collection reasons?

tap4154
September 16th, 2010, 10:27 PM
All this dribble, "Death Caps" Danger, Danger, Danger!!!!
Complete nonsense!
Search for yourself, not one person killed by a Fender amp can be found.

I found this, very entertaining, the amp was powered up, the guy stuck his finger in it.

http://www.youtube.com/watch?v=1lozkT1zrIU

So, where are all the dead bodies?

Gotta say, you may be a master amp builder, whatever, but I see electricians with your attitude all the time, and I steer clear of them. But I do always get a kick watching those that insist on not turning off breakers, and watching them jerk away ten times, trying to be macho, I guess. I just don't get it.

And no, maybe there's not that many reported deaths, but then only the big names would make the news. Who knows how many amateurs were killed or seriously injured by old amps, not to mention; why even take the chance?

I just hope you're not a tech in my area.

Martin R
September 17th, 2010, 12:36 AM
Guys, I understand and accept that 3 prong cords are the accepted safety standard today and I don't mean to be contrary-I really don't know jack compared to some of you who do. But I do have to ask: has something happened to the nature of electricity or how wiring is done to increase this danger in the last however-many years? It just seems that players would have been dying left and right back in the day...

Also, is there anything one can do to increase his odds of living with a 2 pronger that he wants to keep stock for historical/collection reasons?

Back in the early '70's I was watching my roommate's band rehearse. The lead player had a Les Paul into something funky. It was in a concrete block room/house, fairly old and out in the boonies. Even had a concrete floor.

He pulled the tab on a beer, had a drink, walked up to the mic, and POW. There was a loud pop and he was on the floor. Everybody laughed and someone flipped the ground switch on whatever grey amp it was and the rehearsal began.

I'd been shocked a few times with an old BFDR and absolutely hated it. But until I saw that I never thought it was particularly dangerous.

Now I have my Deluxe noverb converted to a three prong with proper ground. I even have a plug in circuit tester for older clubs and venues.

Do what you want, I have better ways to fry my brain.

jefrs
September 17th, 2010, 01:53 AM
Missed this Jupiter, sorry...

You will be much better off making sure your amp is plugged in 'the right way', and also making sure everything is plugged in 'the right way' that's in your chain.

Just wondering, do the plugs over there have fuses inside?

UK plugs are fused at the equipment rating, few other countries bother with that, and most of our "wall-wart" PSU are not fused.

There is a subtle but important difference between UK/European mains and that in the USA :-

Left-pond is something like 110-120VAC, this is 60-0-60 i.e. you can draw current between either rail and earth "non-polarized" and how-come they get electric shocks when the mix their 2-pin plugs around.

Right pond is 230VAC "Euro" (but 245VAC in UK) but this is like 0-240 i.e. the neutral is "earthy", you cannot get a shock between neutral and earth (but I have measured over 50V on a faulty neural rail). UK mains plugs are fused on the Live, and distribution switchboards are fused or RCD breakered on the Live. UK plugs are fused, few other countries bother with that, and most of our "wall-wart" PSU are not fused.

Other countries follow one or the other system, have their own plugs and wiring colour scheme, e.g. Australia follows UK practice with 240VAC.

If you take your amp to play in some old hall in the UK, then the stage power should be from one phase only, but some of these old places are well-dodgy: you should take you own plug-in RCD breaker (not a polarity tester) - these can handle over 3kW so you can probably run an entire band on one. You should all use the same phase because you can draw current between phases (we have three phases). An RCD will trip before you can get a lethal electric shock (electrocution = dead). An RCD will trip in milli-seconds if there is any current flowing on the earth or the current on the live does not match that on the neutral.

We only set our own mains standard ca 1960, since then we now have European safety standards for wiring using a polarized supply with earth and polarized plugs. America has adopted a similar system but is taking a long time to catch up. There seems to be a lack of belief that what they were doing before was dangerous.

And that is the most important thing: electricity can kill you.

65flh5326
September 17th, 2010, 02:10 AM
[QUOTE=tap4154;2754872]Gotta say, you may be a master amp builder, whatever, but I see electricians with your attitude all the time, and I steer clear of them. But I do always get a kick watching those that insist on not turning off breakers, and watching them jerk away ten times, trying to be macho, I guess. I just don't get it.

And no, maybe there's not that many reported deaths, but then only the big names would make the news. Who knows how many amateurs were killed or seriously injured by old amps, not to mention; why even take the chance?

I just hope you're not a tech in my area.

Again, where are the deaths traced to Fender amplifiers with 2 prong plugs being the sole cause!
There are none, not one. If there was even a few killed, Fender would have hell to pay years ago, all amps would have been recalled and corrected.
So, what big chance or risk is there?
You are not happy, because I challenge the out right lies or untruths that are being expressed here by the fear mongers.

"I do always get a kick watching those that insist on not turning off breakers, and watching them jerk away ten times, trying to be macho, I guess. I just don't get it."


I certainly do not operate anything like that.

The direct current thyratron tube, machine tool drive I pictured above is usually powered by 460 volts 3 phase.
There are 88 circuits with voltages to 580volts. There is no way to work on them not powered up.

One can electrocuted being in contact with a grounded appliance by contacting another appliance that is faulty.
Due care is always important when being in contact with multiple energized items.
I am saying, Fender amps with 2 prong plugs are not killing people, there is no proof of that at all.

"I just hope you're not a tech in my area."

If you do not have one of these, we will never meet.
http://i170.photobucket.com/albums/u265/donsmonarch10ee/Don006.jpg

smokerjoe34
September 17th, 2010, 02:21 AM
Again !! Is the 3 prong adapter any good ??? U know the 1 that changes the cord from 2 prongs to 3 prongs ??

65flh5326
September 17th, 2010, 02:55 AM
"Again !! Is the 3 prong adapter any good ??? U know the 1 that changes the cord from 2 prongs to 3 prongs ??"

I know of no adapter that does that. Its the other way around 3 to 2.

Tim Bowen
September 17th, 2010, 04:12 AM
In the early 90's, I went to a first rehearsal with a brand new band and a brand new '52 RI Telecaster, and couldn't wait to get started. It was at a nice little house in a charming old Atlanta neighborhood, but apparently, the electrical wiring was from Warren G. Harding's term in office. I flipped the switch on an old blackface Twin with a two-pronger and grabbed the guitar by the neck. My hand stuck and I was filled with juice. Not sure how long it went on, but it felt like my heart was about to burst. Fortunately, the bassist eventually had the presence of mind to yank the plug out of the wall. I stumbled out on to the front lawn, barfed, and my new guitar and I fell right in it. Then I passed out.

That was the end of that day's rehearsal, and the last time I played an amp with a two prong plug. I'll choose being above ground over tone any day of the week.

DenisS
September 17th, 2010, 08:15 AM
Guys, I understand and accept that 3 prong cords are the accepted safety standard today and I don't mean to be contrary-I really don't know jack compared to some of you who do. But I do have to ask: has something happened to the nature of electricity or how wiring is done to increase this danger in the last however-many years? It just seems that players would have been dying left and right back in the day...

Also, is there anything one can do to increase his odds of living with a 2 pronger that he wants to keep stock for historical/collection reasons?

That was a simpler and more slow-paced time. The outlets in houses were two-pronged at that time. When we heard too much hum we turned the plug around. Now we take our little amp to an open-mic and then what - stop the proceedings to check polarity?

Yes, if we check the polarity every time on all amps in the band everything will be fine. A good way to do this is to turn down the gain or volume on the amp and plug in your guitar cord with the other end laying naked on the floor. Turn up the gain until you hear hum/buzz. Turn it down again and switch the polarity or turn the 2-prong AC plug around and try it agian. The way that gives the least hum is the correct polarity. If you don't get enough hum to tell, you can buzz the open end with your hand to get more - watch the volume! Or you can use a meter or neon tester to go from your amps' chassis to a good ground. Maybe the floor of a basement, water pipe, radiator, or maybe a metal switchplate if the house is wired right.

Safety first sounds trite and nerdy, but it's absolutley essential. In my trade I see people get hurt or die by shocks or getting sucked into conveyor belt mechanisms for lack of mindfullness on a regular basis. I'm surprised at the cavelier attitude of 65flh5326 as he works with machine tools and should know better that to jeer at safety. I'm one of those guys who has to work while hanging in the air on the metal trusses of machine facilities on live 3-phase 480 volt systems from time to time. There are times when we literally can't stop the presses. My body knows how to move around electricity from 40 years of practice, but I am still carefull as all get-out. Trying not to become a statistic. So this is a worthy thread to me.

tap4154
September 17th, 2010, 10:14 AM
In the early 90's, I went to a first rehearsal with a brand new band and a brand new '52 RI Telecaster, and couldn't wait to get started. It was at a nice little house in a charming old Atlanta neighborhood, but apparently, the electrical wiring was from Warren G. Harding's term in office. I flipped the switch on an old blackface Twin with a two-pronger and grabbed the guitar by the neck. My hand stuck and I was filled with juice. Not sure how long it went on, but it felt like my heart was about to burst. Fortunately, the bassist eventually had the presence of mind to yank the plug out of the wall. I stumbled out on to the front lawn, barfed, and my new guitar and I fell right in it. Then I passed out.

That was the end of that day's rehearsal, and the last time I played an amp with a two prong plug. I'll choose being above ground over tone any day of the week.


But you weren't killed, so your experience doesn't "count", our "cowboy" electrician would say. Or I'm sure he'll come up with some other diversion to defend his promotion of not updating old Fender amps.

And 3-prongs adapters are basically just a way to avoid cutting the ground prong off to plug into an old non-grounded outlet. Even if you use the faceplate screw to attached them, the outlet box may not be grounded, which means your amp isn't grounded.

Anyone who's been hit hard by "juice", as I have as well, doesn't give a damn about anyone calling them a pu$$y for being safe with electricity. That's elementary school mentality IMHO.

Stan Martin
September 17th, 2010, 11:54 AM
http://www.unclespot.com/2to3prongconversion.html

Tim Bowen
September 18th, 2010, 05:08 AM
But you weren't killed, so your experience doesn't "count", our "cowboy" electrician would say. Or I'm sure he'll come up with some other diversion to defend his promotion of not updating old Fender amps.

And 3-prongs adapters are basically just a way to avoid cutting the ground prong off to plug into an old non-grounded outlet. Even if you use the faceplate screw to attached them, the outlet box may not be grounded, which means your amp isn't grounded.

Anyone who's been hit hard by "juice", as I have as well, doesn't give a damn about anyone calling them a pu$$y for being safe with electricity. That's elementary school mentality IMHO.

For the record, I was more about relating my personal experience with my post than I was about rolling around in the mud as to the technical or ethical debates at hand. But since you've addressed my comments, I can't say that I disagree with your sentiments in the least.

It's one thing to have done the math and decide for oneself which way to go with electrical current. However, we should keep in mind that our words here are read by fifteen year old kids and novices, as well as by seasoned veterans like you and me that have damn near fried themselves - on a daily basis, across the planet. To champion the cause of potentially unsafe practices - in the wrong hands (and there are more that will be wrong than will be right) - is a highly irresponsible cause to beat the drum for, to say the least, in my estimation.

You're absolutely right - I did survive. This is because I was surrounded by other people, and one in particular had the common sense to yank a plug out of an outlet. Had I been alone at the time, I don't think it's a stretch at all to speculate that I might've picked up a guitar for the very last time seventeen years ago.

Even the outside chance of making the wrong call - it's simply not worth it.

Captain Bb
September 18th, 2010, 05:51 AM
If you wanna keep the 2 wire option and be safe, then why not just fit a 2 wire GFCI (Ground Fault Circuit Interrupter) to your amp power cord?

postjob62
September 18th, 2010, 08:12 AM
If you wanna keep the 2 wire option and be safe, then why not just fit a 2 wire GFCI (Ground Fault Circuit Interrupter) to your amp power cord?

Well, just to be honest, because until reading your post I had no idea such a thing existed. This is exactly the sort of info I was asking for!

Thanks, man. Done deal!

Captain Bb
September 18th, 2010, 02:56 PM
Gad to have been of help.

If you get the type that's built-in to a power plug, then you only need to replace the existing two pin plug on your cord and you're safe to go.

After watching our lead guitarist nearly get fried I've had them fitted to all the power distribution leads for our band so everyone is protected.

DenisS
September 30th, 2010, 07:40 AM
If you wanna keep the 2 wire option and be safe, then why not just fit a 2 wire GFCI (Ground Fault Circuit Interrupter) to your amp power cord?

Captain - you hit the nail with your head :razz:

scrapper
November 18th, 2011, 01:25 PM
I have early 70's Fender Super Reverb amp with a 2 prong plug. I was wondering if converting to a 3 prong plug might eliminate the loud hum I get when plugged in with single coil guitars like my Les Paul Jr?

Thanks!

telex76
November 18th, 2011, 02:00 PM
I have early 70's Fender Super Reverb amp with a 2 prong plug. I was wondering if converting to a 3 prong plug might eliminate the loud hum I get when plugged in with single coil guitars like my Les Paul Jr?

Thanks!

Probably not, unless you have the 2 prong turned the wrong way.

markos
November 18th, 2011, 02:13 PM
I insist on changing out the 2-prong cord, but I keep the polarity switch in there [with that death cap] because I rarely have the opportunity to plug into grounded outlets. My apartment here in Denmark has only the 2-prong types, so I find the polarity switch works great. I don't know why, but reversing the plug in the wall doesn't do the trick??? Good news though is that there is a ground fault interrupt device for the entire apartment.

jefrs
November 18th, 2011, 02:53 PM
I insist on changing out the 2-prong cord, but I keep the polarity switch in there [with that death cap] because I rarely have the opportunity to plug into grounded outlets. My apartment here in Denmark has only the 2-prong types, so I find the polarity switch works great. I don't know why, but reversing the plug in the wall doesn't do the trick??? Good news though is that there is a ground fault interrupt device for the entire apartment.

Because you have 0-220VAC and can earth the neutral, whereas left-pond they have 55-0-55 VAC, and can earth either side.

Reversed, you are playing with a live "earth", your chassis is hot.

They can reverse the polarity and still have an earth whereas you may end up killing someone. You may have a ground faulty interrupt breaker but without a ground wire (3-pin) it's as much use as a chocolate teapot.

Get your apartment re-wired to regulation standards asap.

jefrs
November 18th, 2011, 03:02 PM
If you wanna keep the 2 wire option and be safe, then why not just fit a 2 wire GFCI (Ground Fault Circuit Interrupter) to your amp power cord?

I may be a bit dim here, so perhaps you could explain just how on earth a 2-wire Ground Fault Circuit Interrupter (GFCI) works without the ground connection :?:

markos
November 18th, 2011, 03:19 PM
Thanks jefrs; Apparently my apartment does meet regulation standards as long as that circuit breaker is in there [my mistake, it's not a ground fault interrupter]. Having arrived here from the US last year, I raised an eyebrow when I found that out. Over there at least the kitchens had grounded outlets, so I could run an extension cord, but here...nothing. I rarely see 3-prong outlets in private homes.

jefrs
November 18th, 2011, 03:44 PM
Thanks jefrs; Apparently my apartment does meet regulation standards as long as that circuit breaker is in there [my mistake, it's not a ground fault interrupter]. Having arrived here from the US last year, I raised an eyebrow when I found that out. Over there at least the kitchens had grounded outlets, so I could run an extension cord, but here...nothing. I rarely see 3-prong outlets in private homes.

I have really no idea how Denmark used to do its wiring, but the EU regs imply that 2-pin outlets ain't got no earth wire. It is a very long time since I've seen a 2-pin plug in the UK, they had no earth (well dodgy), used for e.g. clocks and some lamps.

So no earth = no ground breaker.

However, by rights the neutral is connected to earth at the substation. That means if you reverse the plug you put the live onto the chassis, eek!
You should also have an earth connection at the house.

http://en.wikipedia.org/wiki/AC_power_plugs_and_sockets

According to Wiki (usually right on electrics and engineering :rolleyes:)
http://en.wikipedia.org/wiki/Mains_power_around_the_world
Denmark uses the unpolarized CEE 7/16 Europlug (CEE7/17 socket), the polarized earthed French and the olde Danish polarized earthed 3-pin

N.B. the flat 2-pin Europlug is only rated for 2.5A and it ain't earthed.
Brilliant bureaucratic idea, not!

Btw the French use a 3-pin "Europlug", with a polarizing earth pin, the socket will accept the flat 2-pin jobbie (qv).

If you ain't got no 3-pin, you ain't got no earth. So the "RCD" earth breaker cannot sense the current on the earth, so it does absolutely _ing nothing.

markos
November 18th, 2011, 04:08 PM
Wow...that's not encouraging. But it's better to be armed with a little knowledge, and watch my ass. So true about the "brilliant" bureaucratic thinking!
You're right on the money about the 3 different plugs used here. For bigger equipment [like my computer and amps] I only seem to see the French/German polarized plug, which fits perfectly into the 2-prong outlet. The only advantage of this is that you are less likely to reverse it. But, it's still not grounded! It's just nuts, but people just shrug their shoulders like I'm makin' a big fuss over nothing.

sheltone60
November 18th, 2011, 06:20 PM
Got a question for those electrical types out there: I have an old Princeton that's got a two prong plug on it. Not really a specific reason it doesn't have three except it came that way and I'm willing to get it changed.

Anyways, usually, when gigging, I keep it plugged into the outlet on the back of the Voodoo Lab Pedal Power 2 which is grounded.

Any sort of safety improvement here or do I still need to get it wired as a three prong?

celeste
November 18th, 2011, 08:38 PM
I may be a bit dim here, so perhaps you could explain just how on earth a 2-wire Ground Fault Circuit Interrupter (GFCI) works without the ground connection :?:

It just compares current flow in the two wires and if they get more then a few micro amps imbalance it will open both legs.

Agave_Blue
November 19th, 2011, 12:03 AM
Got a question for those electrical types out there: I have an old Princeton that's got a two prong plug on it. Not really a specific reason it doesn't have three except it came that way and I'm willing to get it changed.

Anyways, usually, when gigging, I keep it plugged into the outlet on the back of the Voodoo Lab Pedal Power 2 which is grounded.

Any sort of safety improvement here or do I still need to get it wired as a three prong?


The outlet has a ground, but the two prong plug isn't grounded, so the amp isn't grounded, regardless of what you're plugging into. Add the 3-prong plug for the general safety and peace of mind.

markos
November 19th, 2011, 11:06 AM
Hi jefrs,

I did some more reading up on things, and it turns out that what my dictionary called a "circuit breaker" is actually something different. What I have in my apt. is a HPFI uncoupler which--if I remember correctly--measures ingoing and outgoing current in the home, and if there is a slight difference [don't remember how much, but it isn't much] then it shuts down the whole grid. It's supposed to shut down everything before the voltage/current reaches a lethal level. We are supposed to test them at least every six months, and they are required in every home. So I guess this is why it's legal to have ungrounded outlets, even in the kitchen. Geez. I still think that sucks. I'd rather have at least a few 3-prongs lying around.

-Mark.

Riffraff12571
November 19th, 2011, 11:20 AM
http://i706.photobucket.com/albums/ww70/2266vm/zap.jpg

:twisted:

Riffraff12571
November 19th, 2011, 11:47 AM
[QUOTE=tap4154;2754872] If you do not have one of these, we will never meet.
http://i170.photobucket.com/albums/u265/donsmonarch10ee/Don006.jpg

Nice chunk of ARN there!

Agave_Blue
November 19th, 2011, 04:21 PM
http://i706.photobucket.com/albums/ww70/2266vm/zap.jpg

:twisted:

I thought you were gonna change that? (Or maybe I'm thinking of a different thread/amp/user).

Riffraff12571
November 19th, 2011, 05:20 PM
I thought you were gonna change that? (Or maybe I'm thinking of a different thread/amp/user).

It was probably me. I haven't done anything to it yet. It looks and sounds like new and has never been touched with a soldering iron so I need to decide if I'm gonna be the guy that takes it's virginity to make it giggable or sell it to a collector.

Bongocaster
November 20th, 2011, 12:48 PM
Did some googling and found one site that said you are safer with a GFCI on an ungrounded receptacle than on a grounded outlet. Of course they were recommending that you have both. I also read that it is acceptable to use the GFCI on the two wire as long as you mark/label the outlet, and any others down line that are protected by the GFCI, as “GFCI Protected” and “No Equipment Ground.”

Went to my music room and inspected. Everything is two wire with no ground and pulling the fuse shows that the lights and outlets for three rooms are all off of one fuse. Yes I did say fuse. Holy poop:sad:

So I grabbed a GFCI that was left over from a project and tried to install it. It would barely fit in the box so I decided to try it on the last box in the line thinking that it would have enough airspace do dissipate heat for one outlet. Bear in mind I said try. Wired it up and hit the test button, and it tripped. Plugged in my GFCI tester and it wouldn't trip. I'm guessing that the GFCI may have been left over because it is faulty and did not fail the tester because it was only on a two wire circuit. Anybody?

Needless to say I took it out and put things back as they were. Meanwhile, since a house rewire is not in the near future, I will use an extension chord from the grounded GFCI, that tests right with the tester, out in the hall that is on the grounded bathroom circuit.

tap4154
November 20th, 2011, 01:02 PM
I am concerned on this one. Because there STILL IS NO EARTH GROUND. The round prong is supposed to be tied directly to an earthing rod outside the home. It will allow you to use a 3 prong plug, but doesn't really allow for the use of the earth gound in case of a circuit failure. Kinda like just sawing off the round prong with a hacksaw and plugging in an old socket.:cry:


Yes, you need a separate ground path. Using the neutral as a ground just doesn't cut it, and is only a "false ground" that may test right, but is not any better than not having the neutral and ground connected at the outlet. You need a separate/alternate path to your Earth ground. Even though the neutral and ground may meet at the breaker box, you still need that separate/alternate ground path to the outlet so in the case of a short in the outlet, amp, or whatever is plugged into the outlet, the juice has another way to go to Earth, besides your body.