Electricians: help me out here...

[Variable]

...So, I recently moved into a new apartment and have been getting shocked when playing guitar. Not when I'm just wailing, but rather when I complete an electrical circuit by touching the metal switch chain of my overhead light, or any exposed metal on my heat radiators (it's an old building). I think what's happening is there is a separate path to ground for the wall outlets than there is for whatever is hooked up to the piping in this building. Does that sound right? The shock I've gotten from my exposed radiator was one of the worst I've ever had, even when I did a crappy job discharging a capacitor in an AX84 build many years ago I don't get shocked if I'm not touching anything grounded through the wall outlet (i.e., guitar, amplifier chassis, etc).

There is also a really silly amount of EMF that is coming off of the radiator in my music room, so I know there is some juice flowing through these pipes.

Obviously I've notified my landlord; I just like to have my homework done in case whoever shows up to look at it isn't the brightest lightbulb on the Christmas tree.

 

[bwgintegra]

a lot of times in homes ground rods are used but also steel water mains that are a certain distance into the earth are used for bonding ground. It all depends on the state codes where you are located. Also some older places get the receptacles updated to three prong but the original conductor is only 2 so you really don't have that bonded ground back to the service panel. Have you ever had this problem with the amp at a different location or place?

 

[Variable]

a lot of times in homes ground rods are used but also steel water mains that are a certain distance into the earth are used for bonding ground. It all depends on the state codes where you are located. Also some older places get the receptacles updated to three prong but the original conductor is only 2 so you really don't have that bonded ground back to the service panel. Have you ever had this problem with the amp at a different location or place?

Nope. In all my years living in apartments, never once have I been shocked through my equipment (other than the aforementioned capacitor discharge episode, which was my own damn fault for being dumb). My last apartment was also old with some bad wiring, and I never got so much as a static jolt there (though it was also crazy noisy with EMF).

I did test the receptacles with a ground tester and they show as good.

 

[bwgintegra]

If you have access to the breaker that feeds the receptacles turn it off and pull out and see how many conductors you have. Also check if its a metallic or plastic box. I'm guessing its a larger issue with proper service grounding. Guessing how old would you say the building is?

 

[Variable]

If you have access to the breaker that feeds the receptacles turn it off and pull out and see how many conductors you have. Also check if its a metallic or plastic box. I'm guessing its a larger issue with proper service grounding. Guessing how old would you say the building is?

Probably built in the 1920s or so. It's Chicago, most buildings are older than dirt

 

[Variable]

Well, turns out I'm not crazy (yet). There's a good 125V AC running through my radiator. Now the fun begins finding where the loose wire lives

Goes to show that you should bring a DMM with you when renting out an old apartment...

 

[maddnotez]

I can't help you but the same shit used to happen to me with this Jackson I had. Freaking worst shit ever.

I always thought it was the wiring or unconnected ground in the guitar. Was using the original livewire hmet 18v back then.

 

[thunda]

Also some older places get the receptacles updated to three prong but the original conductor is only 2 so you really don't have that bonded ground back to the service panel.

This. The neutral is not bonded to ground so you become the conductor to ground. BTW, 115 - 130 volts at 60 hz is the perfect combination to STOP your heart.

 

[Variable]

Also some older places get the receptacles updated to three prong but the original conductor is only 2 so you really don't have that bonded ground back to the service panel.

This. The neutral is not bonded to ground so you become the conductor to ground. BTW, 115 - 130 volts at 60 hz is the perfect combination to STOP your heart.

I'm well aware. I emailed my landlord not fifteen seconds after regaining my wits. Though the guy who came out today seems to think there may be a loose wire contacting the radiator/water pipes. The ground pin tests good on the actual power outlets. When he hooked up his DMM to the radiator and one of the outlet grounds, it registered 126V AC.

 

[glpg80]

115V AC is fine. The reason it is such a low voltage compared to 408/208/220 3 phase is because there is plenty of time between zero crossings for you to let go.

The dangerous stuff is DC as you cannot overcome the contraction of the muscular response to the electric field magnitude generated by DC. Once you grab on you lose all muscular control. If you allow current to cross your chest, your heart is no exception.

I've been hit with 50,000V and although that was not a fun experience I am still here. I've also played with van de graaff generators that produce in excess of 100,000V - but it is at such low current it is non lethal.

When people say these amplifiers are extremely dangerous now you know why. DC, 5x the wall voltage, and high current.

 

[glpg80]

To the OP - what has most likely happened is someone replaced 2 prong outlets with 3 prong outlets but mixed the phases and/or did not reference the outlets to ground as required by building code inspection. Usually appliances reference neutral to ground and are required to mark the connection to comply with IEEE standards. This should throw breakers should the chassis ever go live by shorting large potential to ground. This is assuming however, that the outlets are referenced to ground themselves and not left open/floating at potential.

When a neutral line is not referenced to ground, the neutral lines are allowed to then float at the same potential as the hot, you then have the problem you're experiencing. With the phase involved, it means neutral becomes hot and hot becomes neutral, and with no references to ground for neutral, you see increased hum or noise from other appliances in the building.

Tell the landlord to get it fixed, as what you have would not pass building code inspection which could involve a lot of headaches.

 

[Anonymous]

The dangerous stuff is DC as you cannot overcome the contraction of the muscular response to the electric field magnitude generated by DC. Once you grab on you lose all muscular control. If you allow current to cross your chest, your heart is no exception.

Yeah, keep one hand out of the amp and in your pocket and be REAL careful when measuring the 466 VDC B+ on pin 3 of your EL34 equipped 100 watter! Otherwise… it could be "bye bye" for you...

Steve

 

[glpg80]

The alternative is CPR lessons for everyone in the family as Christmas presents

 

[Anonymous]

The alternative is CPR lessons for everyone in the family as Christmas presents

Not a bad idea for my house, actually…

Steve