[JaLu]

To Ground, or NOT to ground, that is the question.

I need somebody (like TKR) with "branch ckt" experience. (I'm an old farm boy, Ham radio, EE 2 yr. dropout, USAF 304x4, 34 yr. Power Co. tech) BUT, the more I look at the NEC code book (art. 250 -- grounding) the less sure I am.

I've seen EE's (with their "PE" stickers) argue with Sr. Licensed Electricians for hours over the "best" way to ground things... and then at a power plant, have them require different methods.

I've run 335' of triplex URD (alum 2-2-4) to my barn. No need for 240v, so I'm using it like a BIG Romex... a Hot, a Neutral, and the #4 as the gnd.

Out at the Xfmr pole, the service drop has a neutral and 2 legs of 120. The primary neutral, and the secondary neutral are both tied to the pole ground -- a big copper plate at the butt of the pole. In my basement panel, the power co. neut. And the ground wire -- to a ground rod -- (AND all the ckts gnds AND neuts) all are common on the big multi-screw buss.

SO, my feed to the barn (actually #6 in the house, and #2 URD from the wall to the trench to the barn) will have the neut AND the gnd tied together in the panel.

In the barn, I've put a breaker panel. The neut and gnd will also be common there.

[F]Do I need a ground rod at the barn? I bought one, but haven't driven it yet. My gut feeling is that it really doesn't matter. The code seems really vague. Is an earth ground a good idea, or a bad idea, required or not?

Thanks J.

[tkrussell]

The neutral, equipment ground and the grounding electrode must only connect together at the enclosure that contains Main Service Disconnecting means, or the Main Breaker, and at a point on the supply side of the main breaker, ie: utility meter or utility transformer.

At the Main breaker is the most typical and practical.


The code seems vague as there are several scenarios that are addressed, and you need to keep your wits about when reviewing Article 250. Read 250.24 for this connection.

So, the connection there is at the panel, assuming the Main breaker is at this panel, is allowed and required, but not allowed is the common connection of the neutral and ground at the subpanel.

You may drive additional ground rods, at the main panel and at the subpanel, but only if connected to the equipment ground.

Earth ground is only for grounding the neutral and creating the zero potential of neutral and equipment ground, but earth is not allowed to be used as a grounding conductor.

[JaLu]

Well, I guess I understand. Thanks TK.

Only problem is that my subpanel doesn't have separate busses for the neutrals and the grounds. I guess I can use the provided buss for the neutrals and use a few Kearneys (ie split-bolts to any "novices" out there) to tie the individual ckt grounds to the big ground wire (I think I bought a #6 or #4) running to the ground rod. I only plan to have 3 or 4 ckts at the most.

[KISS]

The instructions will usually tell you how to isolate the neutral. Then you will need a ground bar kit for the sub-panel available separately. Check the mfr's website and/or your supply house.