Multi-pupose wire: GEC and EGC

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Volta

Senior Member
Location
Columbus, Ohio
Hi y'all- been a while, hope everyone's well.


So, I thought that in 2008 or so some text was added to prevent us from using an EGC as a GEC, or vice-versa. Is that so? I can't find it in 2011.

Now, I can't think of any reason not to- in this instance I would ground my seperately-derived system (75kVA xform) with a #2 (because 3/0+1/0 derived) and use the same conductor as the primary's EGC.

The steel in this building is inaccessible. Why run a #2 GEC and a #6 EGC (for primary feeder) for 160' together to land within feet of each other?
 
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hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
To me if the OP has a metal raceway back to the service which will serve as the EGC per 250.118 then he runs a #2 sized in 250.66 in this same raceway to serve as the GEC I don't see a problem?

Of course as long as he adheres to the requirement's for a raceway containing a GEC like 250.64(E)?
 
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hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
George Stolz said:
250.121. No decent substantiation I recall.
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George Stolz said:
As I recall, the panel just took it as a given that it was obviously a no-no. :roll:
Click to expand...

OK so an EGC can't be used as a GEC which maks sense as we are dealing with two differant sizes 250.122 verses 250.66 and in most cases the GEC will be the larger of the two, BUT!
Why can't a GEC sized per 250.66 be used as a EGC? we do this with existing two wire receptacles, is there anything that prevents it if the GEC is sized per 250.66? someone show the code for that one?
 
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__dan

Banned
The GEC terminates load side at the same point as the system bonding jumper (xfrm common grounding busbar) and line side terminates either on the grounding electrode or common grounding busbar that has the jumper to the grounding electrode. If sized appropriately, runs with no splices, enclosing conduit is maintained electrically continuous with bonding bushings and coincidentally takes the same path and terminating points as the EGC, I will not cite it as a code violation (typical for one tranny fed directly from service equipment).

However, if your EGC does not land one end at the same point as the SBJ, other end does not land at the grounding electrode or the busbar with a jumper to the GE, has splices, too small for a GEC, conduit continuity done but not in a compliant manner, has a measurable circulating current violating 250.6, (typical large facility) if you claim that EGC is also a GEC, I will cite that list.
 
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Volta

Senior Member
Location
Columbus, Ohio
hurk27 said:
OK so an EGC can't be used as a GEC which maks sense as we are dealing with two differant sizes 250.122 verses 250.66 and in most cases the GEC will be the larger of the two, BUT!
Why can't a GEC sized per 250.66 be used as a EGC? we do this with existing two wire receptacles, is there anything that prevents it if the GEC is sized per 250.66? someone show the code for that one?
Click to expand...

Well, I think it is just the first sentence of 250.118, as reinforced by 250.134(B). But I don't see why. :blink:
 
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