two sets of SE conductors and GEC attachment

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electrofelon

electrofelon

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Cherry Valley NY, Seattle, WA
Does the NEC address the attachment of the GEC to paralleled services or services with two sets of service conductors, that is does it specify that the GEC must be bonded to all neutrals, not just one, or is this just considered common sense?
 
I've often wondered that too. In the past, I would run the GEC to both neutrals in a two panel scenario. However when you think about it, since the neutrals are originating from the same point, that may be redundant. I'll be interested to see the other replies here.
 
electrofelon said:
Does the NEC address the attachment of the GEC to paralleled services or services with two sets of service conductors, that is does it specify that the GEC must be bonded to all neutrals, not just one, or is this just considered common sense?
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It would be imposable not to bond both neutrals to the GEC in a paralleled service.
 
Yes, as long as the GEC is bonded to one neutral, it will be bonded to all others since they are electricallyy joined at each end - but that is not the issue. The issue I see is that if you only bond to one neutral, that neutral is only half of the conductor - similar to tapping only half of a paralleled feeder, which is definitley against code.
 
Well this is really just a hypothetical question. Usually I run the GEC to near the main panels and run GEC taps to each disco, but I was just thinking about the connection if it were made somewhere between the weather head and the panels.

I just hought of this: If it were acceptable to bond the GEC to just one of two paralleled neutrals (or one set of SE conductors), then why does the NEC give the option of the GEC tap method? You could then just hit one disconnect with a full sized GEC and there would never be a need for GEC taps. How is my logic?
 
electrofelon said:
...then why does the NEC give the option of the GEC tap method? You could then just hit one disconnect with a full sized GEC and there would never be a need for GEC taps. How is my logic?
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I like the option, because the bars don't always accomodate a #1/0 copper (in the case of a 400 amp service), and I can run a #1/0 near the panels and H-Tap a #4 to each panel and it will fit in the hole in the bar. Plus, a roll of #4 solid copper is normal truck stock, so I could run a #4 from each panel on a 400 amp service to the metallic water line entrance, for instance, without getting a piece of #1/0 copper.
 
The tap method is also there for when you don't have any or much neutral load. The neutral to each panel must be sized per 250.66 based on the ungrounded conductors serving that panel. If you have two parallel 200A panels, your neutrals must be at least #4 copper. But if this is a 400A service, you need a 1/0 GEC. Putting a 1/0 GEC on a #4 wire is pointless. So you must either put a 1/0 GEC at a higher place in the service neutral where the neutral is at least 1/0 in size, or use the GEC tap method with two #4 GEC's.
 
suemarkp said:
The tap method is also there for when you don't have any or much neutral load. The neutral to each panel must be sized per 250.66 based on the ungrounded conductors serving that panel. If you have two parallel 200A panels, your neutrals must be at least #4 copper. But if this is a 400A service, you need a 1/0 GEC. Putting a 1/0 GEC on a #4 wire is pointless. So you must either put a 1/0 GEC at a higher place in the service neutral where the neutral is at least 1/0 in size, or use the GEC tap method with two #4 GEC's.
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Thanks, Mark. The more I read of your stuff over the years, the more I appreciate your responses. I'd have never thought of that explanation, as my normal practice is to run full size neutrals. Thanks a million!
 
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