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Ok here is the scenario. My cousin works for the Chicago water department , last night he was thawing out a water main from the main to the b-box. The house right in front of him had the power go out and smoke was coming from the riser out back. Now they use a welder set at 225 volts and run it between 18-20 amps to thaw the main. Could this be a result of a bad neutral on the poco side or even in the meter can? Sorry for long post.
 

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This practise has been around since we started burying steel water lines . I am surprised the city is still using it. Of course the water is hot coming in to the house , they just heated the whole line up. There shouldn't be any current flow to the house , the current should be contained to the welder leads , but with a bad connection , absolutely . How many of you guys as kids thought you would help tack a price of metal on a project without gloves and got lifted because of it. It is dangerous in the right situation for sure.
We now bond waterlines so there's your current path!!
 

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When you use a welder to thaw water lines you can't know the current path. It is often via the electrical system and not the intended path of the water pipe. The welder connections are typically, for the thawing of a building water service, inside the building and the main or a fire hydrant outside of the building. If you are thawing a main, the connection is often two fire hydrants or two valve boxes. If there is a poor connection between those two points on the water pipe, then the current may flow via the water pipe bonding connections in one building and the utility grounded conductor and back to the water pipe system in a different building. This current is often high enough to heat the GEC and or grounded conductor to the ignition point of wood or other combustibles.

After two house fires in adjacent buildings in the same year our city prohibited the use of welders for pipe thawing.
 

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Who is stupid enough to spend long periods of time living where you have to thaw out your water pipes ? :laughing:


I mean , what's up with that?

 
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