250.32

[jap2525]

Everytime I feel like I understand this section,I talk myself out of it.My brother built a garage remote from his house.The house has a 200amp 30 circuit outdoor rt mainlug panel which is fed from a 200a combo metercan mounted on a pole out in the field.There is (3) 3/o's and (1)#4 thhn copper feeding the panel on the house in 2" pvc from the combo meter,neutral and ground are seperated at the house panel.we installed a 2pole 100amp breaker in this outdoor panel and ran "2 urd (3) wire no ground from the house panel to the garage.
there are no continous metal paths between the house and the garage,we stubbed down 1 1/4" pvc at both ends and direct buried the cable between.At the garage we lb'd inside to a 20 circuit 125 amp mainlug panel where at least 10 circuits are being used.We drove a ground rod at the garage and bonded a #6 ground wire to the neutral bar in the garage panel.This was all done before I got into the electrical field. My question is was a main breaker required in the garage panel as per 230.70? even though we had the 2p 100a breaker at the house? also 250.32d (1) states that the neutral to ground connection shall not be made????????.does 250.32d apply only to buildings with disconnecting means and if so what difference does it make. Thanks! sorry this was so long.

 

[steve66]

Re: 250.32

I don't mean to preach, but I hope you understand why you should have hired an electrician to do the work since you said you did it before you were involved in electrical work. Sometimes the requirements are even hard for professionals to understand.

The wires from the house to the garage are not service conductors, but feeders. Thus, 230.70 does not apply. 225.31 and 225.32 would apply, and it sounds like a disconnect would be required at the garage.

It looks like 250.32(B)(2) allows you to run the 3 wires without the ground, and do the grounding the way you did IF you had a disconnect at the garage. 250.52(D) would not apply. Even if it could apply, it would require a separate grounding wire ran to the garage.

So the only error seems to be not having a disconnect at the garage.

(This is per the 2002 code. When you did the work may have an effect on what would have been allowed).

Steve

 

[jap2525]

Re: 250.32

Why would a disconnect at the garage make a difference on how a feeder is grounded?

 

[steve66]

Re: 250.32

Forget the disconnect for a second. The real difference in grounding for a second structure is weather or not an equipment grounding conductor is ran. If you run an EGC to the second building, you do not want to bond it to the neutral at the separate building. If you did, there would be two connections between the EGC and neutral - one at the first building, and one at the second. That would put these two conductors in parallel, and in effect, there would be no difference between the two. Normal current could flow on the EGC when it should only flow on the neutral. Fault current could flow on the neutral when it should flow on the EGC.

Now look at 250.32(B). Part (2) tells you when you can get away without an EGC. Part (1) tells you that if you do have an EGC, don't reconnect it to the neutral at the second building.

250.32(D) is completly different. It is only used when you use exception 1 or 2 of 225.32 (i.e. no disconnect at the separate building). And I don't think you can use those for a garage. If you were using one of those exceptions, 250.32(D) requires an EGC. Thus, you do not reconnect it to the neutral, just like in 250.32(B)(1).

Steve

 

[jap2525]

Re: 250.32

I agree with everything you are saying,I feel the same way,and i install seperate neutrals and grounds once past the main service point,,,,,but in the handbook,exhibit 250.16 under
250.32a and exhibit 250.19 under250.32d both seem to be dependant on where the disconnect is located,or if there is a main disconnect in the outbuilding.So again I ask what difference does it make where the disconnect is located for an outbuilding on how it is grounded.The grounding shown for a disconnect remote from a building as in exhibit 250.19 is different than the one shown in exhibit 250.16 where each panel has a main disconnecting means.I always pull a ground wire in with my feeders now,but the question could arise of why pull a ground if you don't have to.