Contact Voltage when water on

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tesla six

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Buffalo, NY
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Licensed Electrician
Got a call from contractor who says his customer complained of "tingling' when tub water running and touching tile wall. I cancelled everything for tomorrow to take a look, because this is serious. Sounded as if they have known about it for a while.
Could be grounded conductor at the main panel or service? or potentially other problem?

I'm thinking:
check for voltage at location of complaint by running the water and putting my probe in the water and other on wall and nearby metal.
Turn off branch circuit breakers and check again.
Examining main grounding system is in tact.

Thanks in advance.
 
Check to see if the service neutral is damaged. Older homes with all copper pipes, those pipes will serve as the neutral if the service neutral is/has failed.

If it's a cast iron tub with an access panel, you can check to see if there is voltage from the water pipes to the tub. If the water lines are copper and the drain lines PVC, the tub could be electrically isolated and at a different potential than the water lines.

There could also be a nail in a branch circuit which is energizing the metal/wire lathe behind the tile, and the water pipe being (hopefully) grounded is causing the tingling.

My sister had this problem, which was "fixed" (by someone else) by driving a ground rod and installing a #4 wire from the hot water pipe at the shower valve to it. It worked and I saw no other obvious problems, so I let it ride.
 
Since you mentioned they get shocked when touching tile wall you likely will be measuring that tile wall in reference to other things. Keep in mind you may need to wet the wall to get similar results to what exists when they are using the shower.

One of first things you probably will try to determine is if the wall is energized or if the water is energized - the other is likely grounded and of course user is just between the two when the shock happens.
 
The final answer

The final answer

Turns out I metered 14VAC between the plumbing fixtures and, got my probe between a caulk joint of the tile to reach a voltage point behind the tile that I'm presuming was the steel mesh. The ungrounded conductor at the bathroom GFI to same point on the wall was your standard voltage... scary stuff. The good news was it was limited to one branch circuit that was for most of the second floor including the bathroom.

End result: After a few hours of investigating to isolate the wiring integrity failure, I needed to make a decision. I disconnected the K&T branch circuit in the load center, and disconnected the K&T that connected the NMB in an attic JBox for the bathroom.
I ran two new branch circuits, one for the bathroom and a second to re-energize the 2nd floor GP outlets. All the time and checking for contact voltage as things were re-energized. By eliminating the section of K&T I couldn't see and running new wiring, it cleared this up.

The customer was living with this contact voltage for years, in fact had a plastic sheet over the plumbing fixtures. he said he only felt tingling when he was under the shower water, but didn't really think it was a serious concern.
 
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