Ground ate/burned through copper water pipe

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  #1  
Old 12-10-15, 01:20 PM
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Ground ate/burned through copper water pipe

Not sure what happened. Never seen this before. I had the service upgraded at one of my buildings about 4 months ago. An electrician did all the work. I had the service disconnected for painting and other repairs until today. The energy company came out an hooked me back up and turned on my service. While they were there my main water service into the building started leaking severely. I had the water service shut off and this is what I found. not sure if they shorted something out and burned up the pipe or somehow the metals didn't like each other and and just by coincidence the pipe started leaking at the exact time they hooked me up. based upon the burn marks on the ground clamp I am leaning towards them shorting something even though the denied they did anything and said there is no way it could have happened.

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  #2  
Old 12-10-15, 01:58 PM
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I am assuming the ground clamp in your pictures was installed by your hired electrician. Looks like the grounding clamp and water pipe are dissimilar metals, hence the corrosion is due to electrolysis. Also , it appears the water line changes diameter near the water pipe's corrosion. Could be another source of corrosion if the metals are different.
 
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Old 12-10-15, 02:03 PM
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You can see that the clamp is listed for both aluminum and copper conductors. Look for the AL and CU.

That .looks like you had some serious current flowing through a loose connection. You should not have had any flowing on the ground. I think some detective work is needed. Is the panel neutral tight? Did the lights brighten or dim when heavy loads were applied ?
 
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Old 12-10-15, 02:06 PM
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It was installed by the electrician and inspected. They are different metals. The pipe is copper, not sure what the clamp is made out of but it is not copper. The change in diameter of the pipe is due to a coupler. Can electrolysis happen that quickly? The water has been on in there for months and only started leaking as soon as they hooked up the power to the pole.
 
  #5  
Old 12-10-15, 02:09 PM
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The clamp was lose. I thought it was due to whatever happened to the pipe. It is possible the electrician never tightened it up properly to begin with.
 
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Old 12-10-15, 02:27 PM
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I see dark residue, likely due to arcing and a loose connection.
 
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Old 12-10-15, 02:34 PM
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It is possible the electrician never tightened it up properly to begin with.
It is possible but there should have been no current flow. I would guess a loose or even disconnected neutral at the first OCPD (main panel or disconnect) or PoCo side. That would have caused current flow and could have caused arching at the loose ground.
 

Last edited by ray2047; 12-10-15 at 06:00 PM. Reason: Add info.
  #8  
Old 12-10-15, 03:30 PM
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You can see that the clamp is listed for both aluminum and copper conductors. Look for the AL and CU.
Agree!

That .looks like you had some serious current flowing through a loose connection.
Agree!

Looks like the grounding clamp and water pipe are dissimilar metals, hence the corrosion is due to electrolysis.
Do not agree!

The ground clamp is made of tin plated aluminum and is approved for use on copper or steel water pipes. Because of the tin plating it carries the AL - CU markings for the wire that can be terminbated on it.

Even with a loose connection, that corrosion looks pretty severe to have happened in only 4 months.
 
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Old 12-10-15, 05:26 PM
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I have seen that problem before.

Do you have a voltmeter ? You should check or have someone check the AC voltage between the pipe and the ground wire before reconnecting. BE CAREFUL.... you may find high voltage there.

The power company.... and your neighbors could be relying on your ground connection for neutral. The problem may be a broken/missing ground wire to a POCO power pole/transformer.
 
  #10  
Old 12-10-15, 05:29 PM
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concerning the corrosion, if it were doing that for a while you would think there would have been a leak of some sort. I saw nothing and thoroughly inspected it for leaks when I had the water service turned on a couple months ago. It all just went at once. The fact that it happened at the same time they hooked me into the pole tells me the utility company did something.

Luckily it is an easy fix. I don't have to dig up the street or sidewalk. There is enough pipe there that I can just solder on another piece and be good. I'll put a valve in and put the ground clamp after the valve just in case this happens again so I can shut the water off.
 
  #11  
Old 12-11-15, 06:37 AM
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I think it is only coincidental that the clamp, which was never quite tight, got jarred at the moment you experienced the leak and the pipe was eaten through just enough to give way at that moment.

The pipe was probably damaged by minute arcing for the last several months as opposed to metal to metal electrolysis. Usually when electrolysis happens between copper and aluminum, the aluminum gets eaten away first.
 
  #12  
Old 12-11-15, 06:45 AM
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Fixing the copper pipe will cure the leak, but the other issue needs to be fixed also. There should be no current on the pipe.
 
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Old 12-11-15, 07:39 AM
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If I just had seen the pitures of the piping, I would have guessed on corrosion from excessive use of solder paste.
It is on other hand indications on great currents her. When I lived in Oslo (Norway) the streetcars sometimes made problems the rails was neutral/ground and carried the DC current in one direction, but sometimes not... It is definitely an idea to carefully measure both DC and AC. It may also be a periodical thing so the ideal would be a logger. Since I not have such logger I would have put in a wire with a quite small fuse between the ground wire, and the piping for a week or so, and keep an eye on it. If the fuse of just a few amps survives a week, it is probably no problem.
On the other hand, not having a proper grounding are definitely a risk so be careful. Are the building in use these days?

dsk
 
  #14  
Old 12-11-15, 08:13 AM
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There would be no need to install a fuse. A simple amp meter could determine if there was current on the conductor.
 
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Old 12-11-15, 08:31 AM
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I didn't see a fuse mentioned but that would be the last thing you would want to install there.
 
  #16  
Old 12-11-15, 08:54 AM
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The fuse are just an indicator, if it blows within a week, you may have a periodic fault. It must not be there as a permanent or long time installation.
Grounding is a safety matter, and a fuse will ruin the safety. The current may even come from other buildings with a ground fault, and a bad grounding, finding the way to ground via your grounding.
Errors in ground system may be a pain!

dsk
 
  #17  
Old 12-11-15, 09:07 AM
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I understand that d_s_k is saying ....

Nevermind...he got there first ;-)
 
  #18  
Old 12-12-15, 06:11 AM
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An open or high resistance neutral can contribute to this. Here is part of a video that demonstrates a energized water line (starts about 12 minutes into a 19 minute video). A Fire Investigator and Electrical Inspector documented what was found after some fires. Very worthwhile watching.
 
  #19  
Old 12-12-15, 07:52 AM
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Very informative. Thanks for posting.
 
  #20  
Old 12-12-15, 02:31 PM
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Very interesting video, thanks for sharing. From all the evidence presented it definitely looks like there's current going to the ground conductor for some reason. 1st thing to do would probably be to get your electrician back to check everything on his side and also make contact with the power company.
 
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