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· Registered
17 Posts
Discussion Starter · #1 ·
Filled the tub with water and then touched faucet:

Result: Got quite a tingle

Dropped one lead into water and checked voltage to faucet handle:

Result: A little over 2 volts.

Check drain ring to ground:

Result: A little over 2 volts.

Check faucet handle to ground:

Result: 0 volts.

So voltage is on drain ring and traveling to ground through faucet handle.

Question: Because this is a cast iron tub you would think all of the metal would be at same potential?

Other troubleshooting done:

I ran a bare #4 copper to the bottom of the tub and wrapped it around the copper drain pipe that was showing the voltage of 2 volts. I then connected that to a known good ground

Result: Voltage disappeared.

I then turned off the main and checked for voltage:

Result: Still had 2 volts with main off.

Reconnected #4 ground and voltage disappears.

Checked copper water lines to ground.

Result: 0 Volts.

The drain pipe runs directly to the sewer line which was replaced this summer with 4" schedule 40 pvc. From the wall of the house in, it is still cast iron.

The copper cold water line is bonded to the panel with #4 stranded copper which is 50 years old.

There is a ground rod outside, but I have no idea what condition it is in. I will have to dig it up. The bare #4 stranded runs through the block wall and to the rod directly outside the wall.

Anyone have any idea what is possibly going on?

I called the utility company and have not heard back from them yet.

Can I just bond the tub drain using #4 copper and drive another ground rod outside the house?

Any help appreciated.


· Semi-Pro Electro-Geek
3,404 Posts
You really should seek professional assistance with this. This is not the kind of problem to be learning on, considering the complexity and the very serious safety issues involved. You misunderstand the difference between grounding and bonding. This is not a grounding issue, it is a bonding issue. I'd suggest searching this forum (and the net) for extensive prior discussion on that point - it's very important. We'd need more information to provide any more specific guidance, though. The 2V potential you have measured is almost certainly not responsible for "quite a tingle" - something else is going on.

· " Euro " electrician
5,369 Posts
I have see this situation from time to time and most case genrally not a excat DIY troubleshooting nature due there are few issues which it not always address quick and many electricians will be more than happy to assist you on this one.

The last house I work on simauir situation what you have now took me a few hours to find the curpit and it was NOT easy to find it. { the next door house have broken EGC with weak netural connection } I know you did call the POCO about this but really I am seriously have a electrician come over and assist you on this one as well.

This is the only safest way to slove the issue and there is more than just a simple troubleshooting on this fourm.

I am not being mean but I have dealt few complexed situation before and some case it much easier have a electrician come out and do this than try to spend a jour{day} or duex in the fourm try to write up a guideline how to slove this.

This part is pretty serious so please heed our understanding of nature of situation what you have there.


· Registered
10,407 Posts
The tub drain flange might not make a good connection with the tub itself because it might be touching only the porcelain coating on top and have plumbers putty and pipe joint compound on the underside.

Because you have plastic as part of the drain system, some metal parts might not be bonded to the grounded parts of the electrical system.

Running extra bare wires for grounding purposes may be done in any place at any time. Using such a ground wire as a bridge between the tub drain pipe, past a plastic section of drain pipe, and down to a known ground can be the final solution. This ground wire needs to be as thick as the power conductors of any nearby circuit, which would typically be 12 gauge.

No need to drive a ground rod. If you do drive a ground rod, it should have a #6 copper wire connecting it to the grounding electrode system (the latter consisting of the fat ground wire coming from the panel and the primary ground rod or water pipe that wire is connected to).
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