Re: Grounding of residential subpanel
From What I'm getting is this subpanel is fed with a 3 conductor H-H-N and the neutral is bonded at the subpanel to the case and the neutral bar. and the egc's are also connected to this bar. now you have a #8 ran to a water pipe from this subpanel as a water ground.It might not meet todays codes but this sounds like that it was code compliant for the "1960"'s yes you will have parallel fault currents on both the water pipes and the feeder neutral because of multible connections in the building. but where in the nec of the 60's is this not allowed? as we have neutral currents on our water pipes that have a commoned connection with a house down the road. I would install a ground rod at the main service bank and size the gec to the service. the problem is that to bring
fault current will return on both the water pipe and the feed neutral
this up to todays code would take running new SE 2/2/2/4 cable from the subpanel to the main service. and seperateing the grounds and the neutrals at the subpanel. and running the water ground back to the main service panel and bonding it there. and in no way do you ever depend on just the earth to take a fault to trip a breaker as the fault has to return back the path it came back to the neutral at the main service and earth will not do this. as was said before.
Wayne A. From: N.W.Indiana
Be Fair, Be Safe
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