Residential plumbing bonding question

I'm thinking that there is a problem with your neutral conductor and that you don't have a very good ground for your service. Another possibility is that one of your neighbors has a problem with their neutral and the current is coming through your pipes.

Is there a garbage disposal unit in this sink? It may be defective.

Aside from that, you have a serious and potentially dangerous situation there and I'd recommend (even though you don't want to) an electrican look at it.

You are taking a very real risk that either someone will be injured, or you will create a fire hazard if there is an inner wall short between wiring and the plumbing.

No. However, I installed a dishwasher several months ago. But I changed the drain trap from plastic to metal at the same time, which bonded the drain fitter to the drain line and allowed me to discover the problem. So the problem may have been there for some time and gone unnoticed. I did shut off the dishwasher circuit, and it had no affect on the problem.

I'm going to try shutting off circuits one at a time, and see if I can isolate the cause. Failing that, I guess I will need to hire a professional.

I did some troubleshooting and found the source of the voltage (actually

But I really don't understand why there would be voltage coming off of the ground on the outlet box. Should I be looking for a fault in the outlet?

Thanks

-Mark

Agreed. I suppose the vent stack _might_ have been an acceptable ground, had the vent stack itself been bonded to the service ground. But it wasn't. And the kitchen sewer line has been replaced with PVC, so the vent stack (1-1/2" galvanized) doesn't even have its own path to earth.

But where is this voltage coming from? It is load-dependant; if nothing is plugged into the offending outlet, then I measure zero VAC between the kitchen faucet and the kitchen drain pipe. The measured voltage varies as I increase the load on the outlet. (These tests were performed with the vent stack ground wire reconnected, of course.) Does this indicate a fault in the outlet? Or is it normal to have 40-60VAC present on an outlet ground when a load is placed on the outlet?

Thanks

-Mark

With K & T anything is possible. It's best not to try and tap off of it for expansion, but it's too late for that. Take a look inside of the outlet box and see if any conductors have the insulation scraped off and might be touching the metal.

"John Grabowski" wrote

I think you're right. I'm guessing that the neutral wire is contacting the box. We'll see.

Thanks for all your help.

-Mark

In the outlet, or anything that was plugged into the outlet. Under normal conditions, there isn't supposed to be any electricity going into the ground. Something isn't right, there. Also, make sure the neutral for that outlet is groud potential. If it has significant voltage on it, it's probably time to call the electrician.