Lighting strike burnt hole in copper water pipe

[Sparkfromtex]

A customer called us stating that he had a plumber come out and repair copper piping under the slab of his home. The plumber told the home owner that his house probably took a lighting strike and because the ground wire is connected to the cold water, it burnt a hole in his water pipe. The customer is telling us he want's us to remove the cold water ground from his pipes so that won't happen again. Any thoughts?

 

[Gregg Harris]

A customer called us stating that he had a plumber come out and repair copper piping under the slab of his home. The plumber told the home owner that his house probably took a lighting strike and because the ground wire is connected to the cold water, it burnt a hole in his water pipe. The customer is telling us he want's us to remove the cold water ground from his pipes so that won't happen again. Any thoughts?

The chances of that happening are slim to none.

 

[ggunn]

A customer called us stating that he had a plumber come out and repair copper piping under the slab of his home. The plumber told the home owner that his house probably took a lighting strike and because the ground wire is connected to the cold water, it burnt a hole in his water pipe. The customer is telling us he want's us to remove the cold water ground from his pipes so that won't happen again. Any thoughts?

A customer should beware of accepting electrician's advice from a plumber.

 

[petersonra]

the chances of this happening under the slab by a lightning strike seems very low, especially if it did not do any other damage.

my guess is just normal corrosion of which there are various types.

that is why many water systems are now run in plastic.

 

[GoldDigger]

the chances of this happening under the slab by a lightning strike seems very low, especially if it did not do any other damage.

my guess is just normal corrosion of which there are various types.

that is why many water systems are now run in plastic.

Unprotected copper pipe in concrete is subject to heavy corrosion from the outside and depending on the chemicals in the heating fluid corrosion from the inside too. The worst inside to outside corrosion will be in bends or transitions. And if a pinhole leak starts, the action of the soaked concrete surrounding it can accelerate the corrosion at that hole, enlarging it quickly.

If there is a long term low potential difference between the piping and the ground potential of the slab, it will accelerate the corrosion. If you measure a significant AC or DC voltage between the ground electrode network and the pipe before bonding, then bonding could well cause heavy corrosion, and the cause of the ground voltage offset needs to be identified before the bond is made.
So the plumber may have something behind his statement, just leave the lightning out of it.

 

[brycenesbitt]

A customer called us stating that he had a plumber come out and repair copper piping under the slab of his home. The plumber told the home owner that his house probably took a lighting strike and because the ground wire is connected to the cold water, it burnt a hole in his water pipe. The customer is telling us he want's us to remove the cold water ground from his pipes so that won't happen again. Any thoughts?

Why not just quote a driven earth ground rod and be done with it? A lot of the energy of any future strike will shunt via the ground rod, even if the copper pipe is still connected.

Note that grounding a pipe can increase corrosion, so the plumber might have been right, even if an actual strike was not involved.

 

[kwired]

Why not just quote a driven earth ground rod and be done with it? A lot of the energy of any future strike will shunt via the ground rod, even if the copper pipe is still connected.

Note that grounding a pipe can increase corrosion, so the plumber might have been right, even if an actual strike was not involved.

The water pipe will have a lower impedance to earth in most cases than a single ground rod will, which is a major reason the NEC requires us to use it as a grounding electrode if it is present.

 

[tom baker]

Some areas have very agressive water and the low PH will cause corrosion of copper. The EPA addressed this 15 years ago and required testing-monitoring- maybe treatment. My water system raised the ph by adding small amounts of sodium hydroxide.
You can contact your water company and get a copy of the consumer confidence report.
Also, AC current is not generally considered to corrode copper but DC will esp if the current is going away from the pipe.

 

[augie47]

Just an observation. Pinholes caused by lightning are a documented problem with CSST gas piping so I don't think it's unreasonable think it might happen to a copper water line, however, the recognized solution to the CSST is proper bonding to the grounding electrode system so one would think a unprotected (no coating) copper line that was in a ground level slab would not be likely to develop a hole but once protected by plastic cover might.
Just comparing CSST and Cooper water.

 

[kwired]

Also, AC current is not generally considered to corrode copper but DC will esp if the current is going away from the pipe.

Well if DC current is not going away from the pipe on one end it must be on the other.

 

[GoldDigger]

Well if DC current is not going away from the pipe on one end it must be on the other.

Ha, ha. :thumbsdown:
I think what counts is whether it is going away from the wall of the pipe into the earth.
Fortunately current flowing the length of the pipe does not count at all, unless the IR losses are large enough that they change the relation of the pipe to earth at one end or the other.

 

[mwm1752]

Just say no

 

[ceb58]

A customer called us stating that he had a plumber come out and repair copper piping under the slab of his home. The plumber told the home owner that his house probably took a lighting strike and because the ground wire is connected to the cold water, it burnt a hole in his water pipe. The customer is telling us he want's us to remove the cold water ground from his pipes so that won't happen again. Any thoughts?

I would ask the customer where the hole in the house is? If it took a direct strike there will be a hole in the house. Ask what else was fried when it took this supposedly lightning strike. If they say nothing was fried tell them to get another plumber.