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The original was posted on /r/electricians by /u/Adotkilla_1 on 2024-01-14 13:48:40+00:00.
So I was doing a 200 amp upgrade yesterday and it was one that had a lot of older circuits, long exterior run, stone house, etc.
Bottom line it was one that I knew would be a long day. We had the exterior all done and once I get most of my breakers landed, I power up the panel and turn circuits on as I land them. (Homeowners came home and have two young kids so I wanted to get as much on as I could it was cold)
We had the ground rod totally done and the last thing I’m doing is the water pipe ground. I noticed the plumbing was recently done from the street and there were 4 water pipe clamps. Old water pipe ground just went to a pipe up high and the plumbers had jumped the meter and also jumped some newer plumbing they had done where they had valves for a water softener and such. All of that plumbing was copper pro pressed together so seemed redundant but I decided to just run my #4 continuously through all of their clamps.
Well when I touch the ground to the first clamp (house side of water meter) it arced slightly. Nothing crazy but definitely some arcing.
My question is what is this arcing from? The house was running totally fine on the neutral so I know it wasn’t a bad utility neutral. Any ideas?
To note it was clear when the plumbers did their work not long ago they found this to be the case hence why they used so many clamps.
Thanks for any responses.