GEC to water pipe melting?

[bcl]

Weird service call I got that I'm trying to research before I show up next week. Customer says that the utility had some issues with a transformer and as far as I can tell, it sent a surge back to the houses in the area. The customer said no equipment was damaged, but that after they heard a pop, water started leaking under their house. The plumber said that he thinks the old water bond sent the surge to the pipe and melted the copper pipes.

The only thing I can think of is that the bonding termination had aged and was loose so that when the surge was sent to ground, it arced and fried the pipe?

I've never heard of this happening, but every time I think I've seen it all, something new comes up.

My plan is to inspect the GEC as much as I can, and probably disconnect any existing GEC to be replaced with two ground rods outside.

 

[tom baker]

More likely an open neutral. First take amp reading on GEC. If you show current do not disconnect. Open neutral can damage equipment. May need to turn off power immediately, contact POCO
Check back here frequently!
Ground rods will not help….

 

[zbang]

It's hard to melt a copper pipe with water in it, probably melted the bonding clamp or conductor.

Ya, this sounds like a TODAY thing, not a next week thing.

 

[ActionDave]

How much current would you have to pass through a water pipe to melt it? They use acetylene torches to sweat the fittings together. I'm not buying the plumber's explanation.

Who's to say the water line wasn't compromised in the first place?

Open neutral is a possibility.
Forget about the ground rods.

 

[bcl]

I agree with the unlikelihood of melting a water pipe, it sounded crazy to me too. I’m not sure why the plumber would have said that except that the homeowners are saying they heard the pop when the power went out, and that’s when the leak started.

I’ve seen open neutrals before but it seems like those always fry the 120 electronics that can’t handle the 240. I’ll definitely check for it when I’m there.

Homeowner says everything is working just fine and POCO confirmed everything is square again, not to say I won’t double check.

 

[winnie]

The open neutral can present as follows:

Community has common underground water pipe. Neutral opens but the pipe provides a solid metallic connection back to the transformer, via customer #1 GEC, then pipes, then customer #2 GEC then customer #2 neutral.

Another possibility is that the utility fault connected primary voltage to customer neutral. High current flowed on the entire grounded

 

[winnie]

Strange

My post cut off halfway, and the system throws an error when I try to post the rest.

Apparently I'm running afoul of the internet dieties

 

[bcl]

The open neutral can present as follows:

Community has common underground water pipe. Neutral opens but the pipe provides a solid metallic connection back to the transformer, via customer #1 GEC, then pipes, then customer #2 GEC then customer #2 neutral.

Another possibility is that the utility fault connected primary voltage to customer neutral. High current flowed on the entire grounded

I see what you’re saying. Then the total current would have carried on the ground all the way back to the transformer.

 

[bcl]

I see what’s being said about the open neutral, still have no idea how this could cause a plumbing leak. Other than if the leak was already there and the homeowner didn’t notice until the power went out, then makes the ever-present “it’s construction so it’s entirely the fault of whoever was at my house last” fallacy

 

[jim dungar]

I agree with the unlikelihood of melting a water pipe, it sounded crazy to me too. I’m not sure why the plumber would have said that except that the homeowners are saying they heard the pop when the power went out, and that’s when the leak started.

I’ve seen open neutrals before but it seems like those always fry the 120 electronics that can’t handle the 240. I’ll definitely check for it when I’m there.

Homeowner says everyettthing is working just fine and POCO confirmed everything is square again, not to say I won’t double check.

A little bit of water in a copper pipe prevents it from getting hot enough to melt solder. There is almost no way for current to melt a water filled copper pipe without causing an extreme amount of steam.
Most likely the plumber didn't want to be involved so the blame was directed to the electrician. What a surprise.

Don't forget to check the neighbors neutrals also.

 

[hillbilly1]

Could have melted the sweated joint, that is probably where the leak is, not the pipe itself.

 

[winnie]

Here is part of my post that didn't make it:

Maybe the GEC clamp to water pipe was corroded or slightly loose, causing a high resistance point and intense local heating or arcing.

When you investigate this, make sure you amp probe any wire before you disconnect it; it could be carrying high current. Consider having jumper clamps available if you do detect current on the GEC but need to remake the connection. Remember that current on the GEC could be coming from the neighbors, and shutting off the main may not be sufficient for safety.

Jon

 

[bcl]

Thanks for the advice everyone!

 

[rambojoe]

Or the plumber just doesnt know what he is reporting...

 

[Joethemechanic]

I popped a hole in a copper pipe one time using a Linc-Thaw with a messed up clamp.

 

[hillbilly1]

My neighbor had a pin hole blown out of his copper gas line by lightning. He just happened to be in his basement were it arced to the termite shield. Luckily the flame was blowing against the block wall, not the wood floor joists!

 

[bcl]

Update. Went to the service call today. Three different adults in the home confirmed that when the surge happened, they heard a buzz and a loud pop. Plumbing leaks are no joke, and did not exist prior to the surge. 3 different leaks sprung at the same time in copper pipes. One at the water heater, one under the sink, one in the foundation. POCO said that a wire was loose and came undone at the transformer...assuming this was the neutral. I know that everyone is saying that electrical couldn't blow copper pipes, but @winnie seems to have spoken to the most likely option IF the electrical could have in any way impacted the plumbing. After further investigation, I found out that a couple years ago the water main was replaced with PEX, which means that whatever cold-water ground used to exist no longer meets the requirements of 250.52(A)(1). The plumbers who are currently working on the house are going to install new water lines in the whole house. This means that the old lines are likely still going to be electrically bonded in some way, but they will be abandoned.

Furthermore, there is no separation between grounds and neutrals from the power-pole to the last sub-panel. Meter and first disconnect are on a power pole approx. 100 feet from the house. No ground run from power pole to house. Neutrals and grounds are bonded at the first disconnect on the house, and at both sub-panels that feed off of that main panel inside the house. I measured 10 amps on the ground at the first point of disconnect on the house. The house has been this way since it was built in 1989. This family has lived there since 1998, and they have never noticed any electrical issues until the surge.

This system needs to be corrected all the way back to the power pole. There is also a very good chance that the homeowner won't be able to afford this all at once.

I know that many of you would not touch this if the homeowner did not agree to do everything a the same time, and I completely respect that. However, I also want to let them know that they need to begin taking steps toward making the system safe, even if they can't do it all at once. I think I would propose beginning with a new GEC system on the house. This needs to happen anyway -250.32 (A) - and as far as I can tell the old cold-water ground no longer meets the requirements of 250.52 (A)(1). I'd tear the walls open to see if I could find the initial GEC bond at the water pipes, and disconnect it when found so that the water pipes in the house...which are no longer actually touching enough ground, are separated from the system.Then I'd install new cables with neutrals to the sub-panels and separate grounds and neutrals. Even if they did everything at once, pulling a ground in to the power pole would probably come last because it is the most difficult to coordinate quickly, since it might involve a brand new trench, etc.

Where would you start?

 

[Joethemechanic]

I measured 10 amps on the ground

I'd tackle that problem first.

 

[retirede]

Depending on water chemistry, copper pipes can erode from the inside at various rates. I’ve removed copper water lines that were so thin I could crush it between my thumb and forefinger. I could see pipe thus eroded get compromised by an electrical event.

 

[don_resqcapt19]

I'd tackle that problem first.

With a common underground metal water pipe in the area, that may not indicate a problem. The common metal water pipe, because of multiple connections back the utility transformer neutral at the other buildings in the area will have a very low resistance, and it is not uncommon to finde 25% or more of the neutral current flowing on the water piping. If there is little to no current on the actual service neutral and current on the water pipe, than you have an indication of a problem with the service neutral.