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#85400 - 06/30/03 06:48 AM 250.32 Q's  
sparky  Offline
Joined: Oct 2000
Posts: 5,308
Building A has a service w/GEC's, and a feeder is run from building B to building A (re; subpanel)

~does said subpanel need a GEC if the building already has one?

~if so, should GEC's from different x-formers be married together?

250.32 Two or More Buildings or Structures Supplied from a Common Service.

(A) Grounding Electrode. Where two or more buildings or structures are supplied from a common ac service by a feeder(s) or branch circuit(s), the grounding electrode(s) required in Part III of this article at each building or structure shall be connected in the manner specified in 250.32(B) or (C). Where there are no existing grounding electrodes, the grounding electrode(s) required in Part III of this article shall be installed.

[This message has been edited by sparky (edited 07-01-2003).]

2017 / 2014 NEC & Related Books and Study Guides

#85401 - 06/30/03 09:30 PM Re: 250.32 Q's  
txsparky  Offline
Joined: May 2001
Posts: 552
Magnolia,.Texas U.S.A.
~ should GEC's from different x-formers be married together?

It is done all of the time. Consider a multi-story building where the building steel is used as the grounding electrode for all of the x-fmers in the building.


#85402 - 07/01/03 05:54 AM Re: 250.32 Q's  
PCBelarge  Offline
Joined: Jun 2003
Posts: 681
Dobbs Ferry, NY, USA

Just a 'dumb question', if there is already service in the building why are you running a subpanel to it from another building? Just curious.


Pierre Belarge

#85403 - 07/01/03 06:17 AM Re: 250.32 Q's  
sparky  Offline
Joined: Oct 2000
Posts: 5,308
Pierre, economics....
the original service (5 meters) is a mess, and at the other end of a long building.

This feeder was available by way of an unsued meter/main nearby

#85404 - 07/01/03 12:17 PM Re: 250.32 Q's  
resqcapt19  Offline
Joined: Nov 2000
Posts: 2,148
Are you in compliance with 230.2 and 225.30?


#85405 - 07/01/03 05:18 PM Re: 250.32 Q's  
sparky  Offline
Joined: Oct 2000
Posts: 5,308
it is a feeder, so 230.2 (i believe) would not apply, 225.30 OTOH...
225.30 Number of Supplies.
Where more than one building or other structure is on the same property and under single management, each additional building or other structure served that is on the load side of the service disconnecting means shall be supplied by one feeder or branch circuit unless permitted in 225.30(A) through (E). For the purpose of this section, a multiwire branch circuit shall be considered a single circuit.

would seem to consider outbuildings downstream of the main service, limiting the # of feeders or branch circuits per stipulations.

there are two building on the same property here, via the same owner, each has a service drop.

Building A is a large long 5 unit apt house w/barn.

Said barn is being supplied from building B's exclusive service, via a feeder to A

what am i missing?


#85406 - 07/01/03 10:33 PM Re: 250.32 Q's  
resqcapt19  Offline
Joined: Nov 2000
Posts: 2,148
In my opinion, you can't feed a building that already has a service with a feeder from a second building. You need to check with the AHJ before making this installation. The code intent is to have a single source of supply for each building.


#85407 - 07/02/03 06:33 AM Re: 250.32 Q's  
sparky  Offline
Joined: Oct 2000
Posts: 5,308
hmmm, well if it is pertinent,i believe the barn that is fed here has been ordered firewalled off from the rest of the building.

#85408 - 07/02/03 07:41 AM Re: 250.32 Q's  
Gwz  Offline
Joined: Apr 2002
Posts: 197
I agree with Don about a building having only one supply source.

BUT, what would happen if a 1 to 1 isolation transformer was installed in the feeder of a second source to a building. Would this be considered separately derived?


100 Service
100 Feeder
100 Separately Derived System
100 Premise Wiring (System)
230 cover utility supplied
250 covers GROUNDING.

and probably other Articles.

#85409 - 07/17/03 07:07 PM Re: 250.32 Q's  
tdhorne  Offline
Joined: Mar 2001
Posts: 345
Maryland, USA
Take pitty on us poor jakes (firefighters) and at least clearly mark both disconnecting means to indicate the two supplies and their locations.

Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison

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