Looking for clarification from our electrical experts on the following.
The subject house is a 1980 home which also has a detached outbuilding (garage/ shop)
Home has a newer 200 amp main service panel.
Detached accessory outbuilding has a distribution panel, 60 amps, 240 VAC.
I have deferred the inspection of the distribution panel to an electrician because the neutral is not floating, as can be seen in the photo.
My question is are there any exceptions that I may have missed, that might allow this configuration.
The reason I ask is that I found an exception in my code check electrical that might apply. But I am not certain that I have interpreted it correctly.
It first says that;
EGC (4 wire feeder) is required between bldgs.EXC …(=exception)
The exception is;
No EGC OK if no continous metal path between buildings.
References are to the NEC 99 and 2002 250.32B1 and 250.32B2
(don’t worry…I don’t quote codes…and these probably don’t necessarily apply…I get that…)
I have always deferred these 3 wire distribution panels with common neutral/grounds…and I never get any feedback saying anything contrary to what I reported. As far as I know the electrician makes repairs.
Oh…and there is no continous metal path (i.e. water line) between these structures.
I just wanted to put this out there for discussion to see if I there is some thing(s) I am not aware of.
Yes. There are exceptions, but you need not concern yourself with that (as a Home Inspector).
If it’s not a four-wire feed, defer it and let the sparky sort it out. Also, there should be a grounding electrode for the panel in a detached building. Did you remember to check for that? It appears as if there may be one. . .
In 2008 that exception is going away but for now it is still legal to connect a sub in an outbuilding with 3 wires assuming no metalic paths that are bonded to the electrical system.
Conduit was plastic…but this is why I deferred. There might be something that I missed. And my other question is what if someone runs water to it in the future? Seems like they all should be four wire systems.
If you have a 3 wire feed you MUST/SHALL bond the neutral. That is your fault path.
If you really read 250.32(B)(2) you see this is a “grounded” conductor (neutral) that you are also using for a grounding conductor. With the possible exception of SE cable the AHJ can say this shall be an insulated conductor, just like they could for the range/dryer exception.
If you ran */2-wg romex I would fail you. If you run */3-wg you have a grounding path.
It is first and foremost your neutral but it must be bonded to the grounding conductor to provide a fault path back to the XO (centertap) of that transformer so you can trip the breaker.
If you “start over” in a new panel with 4 wires (from 3) the neutral and ground get connected
