House with what appears to be 4 sub panels. The first one is right next to the main panel and it’s a 50amp for the well. Then there’s two 100amp panels in the house and one 100amp in detached garage. The SEC conductors and the meter about 50 yards from house. That’s were the first means of disconnect is. 200amp breaker with 3 100amp and 1 50amp
breaker The legend is not labeled. As far as I understand, all four of those sub panels need to have the ground and neutrals isolated. The reason I hesitate is because there is a off peak meter on the house for the radiant heat and hot water heater which I am not familiar with so I’m wondering if that changes anything. Also the electrician was extremely meticulous and the service was ok’d but an inspector. Is there anything I’m missing that would make any of these “sub” panels not requiring isolation?! Image_1600701888906|666x500
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Yes, a 3-conductor feeder going to a remote panel in a detached (from where the main is) structure without any metallic paths back to the main. This exception was removed in NEC 2008 In such installation the neutral must be bonded to the remote panel.
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I agree, pre-2008 NEC it can be made compliant with only a 3-wire feeder. 2008 and beyond 4-wire feeder is required. The “neutral” bar in the bottom of photo #3 is a violation. I’m willing to bet that large white conductor in photo #2 had some strands removed to fit in that neutral bar.
Why is “neutral” bar a violation? can you only do that with grounds?
Yes that’s correct, only the EGC’s can use the metallic enclosure as a current path. The enclosure is not permitted to be carrying the neutral current.
But in this instance the neutrals and grounds are bonded together, so why would that not be permitted?
Because the neutral current is flowing on the metal enclosure through the green screw and back to the neutral. The metal enclosure can not be used as a normal path for the neutral current.
200.2(B) Continuity. The continuity of a grounded conductor shall not depend on a connection to a metallic enclosure, raceway, or cable armor.
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So the green screw needs to be removed in the sub panel?
yes… … …
Under normal conditions with a 4-wire feeder to the panel yes. With older panels that are fed with only a 3-wire feeders the answer is no because in doing so the system would be ungrounded. Even though there is a 3-wire feeder to the sub-panel it’s wired like a service with a bonded neutral.