250-50

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monkey

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Situation: 2 100 amp services mounted side by side on a duplex. A GEC is run from service #1 to first grd rod. Another GEC is run from service #2 to second rod. The two services are then bonded with a jumper between them. All are terminated on the buses. Does this violate 250-50?

Also question #2, What exactly is meant by 250-24(a)(3)?

Thanks.............Brian
 
Re: 250-50

Originally posted by monkey:
Situation: 2 100 amp services mounted side by side on a duplex. A GEC is run from service #1 to first groundd rod. Another GEC is run from service #2 to second rod. The two services are then bonded with a jumper between them. All are terminated on the buses. Does this violate 250-50?
Click to expand...
I suspect that that does violate the language in 250.50 because the electrodes are not bonded together.

Also question #2, What exactly is meant by 250-24(a)(3)?

Thanks.............Brian
Click to expand...
250.24 "Grounding Service-Supplied Alternating-Current Systems.
(A) System Grounding Connections. A premises wiring system supplied by a grounded ac service shall have a grounding electrode conductor connected to the grounded service conductor, at each service, in accordance with 250.24(A)(1) through (A)(5).
(3) Dual Fed Services. For services that are dual fed (double ended) in a common enclosure or grouped together in separate enclosures and employing a secondary tie, a single grounding electrode connection to the tie point of the grounded circuit conductors from each power source shall be permitted."

I believe it means that a service that is supplied from two sets of service conductors such as from different transformers may be grounded at the common point on the grounded conductor that would otherwise be technically on the load side of each service disconnecting means.
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Tom Horne
 
Re: 250-50

Do these two 100A panels have their neutrals connected (or is there only one set of service entrance conductors that then splits to two meters and panels)? If so, then I would think 250.142 would allow that common neutral to be considered a bonding wire tying the two GEC's together as long as its sized per 250.66 for the largest ungrounded conductors of the whole service.
 
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