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#210209 - 06/03/13 11:39 AM NEC Article 490
akmaster Offline
Member
Registered: 06/11/12
Posts: 70
Loc: alaska
Hi,
Is it a requirement that raceways entering metal enclosed switchgear over 600 VAC be in rigid conduit or can I come from a transformer to a 4160 switch with duct bank comprised of PVC and bell end reducers?

Here is an article on this:
http://books.google.com/books?id=h2G2PdO...490&f=false

Thanks

Greg
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#210218 - 06/03/13 04:55 PM Re: NEC Article 490 [Re: akmaster]
gfretwell Offline


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Registered: 07/20/04
Posts: 9039
Loc: Estero,Fl,usa
I don't know of anything about metal enclosures and plastic raceways other than the need for a hard wired EGC connected to a dedicated terminal in the enclosure.

OTOH going the other way (metal raceway, plastic box) is a tougher sell. You need a positive way of bonding the raceway.
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#210226 - 06/04/13 10:32 AM Re: NEC Article 490 [Re: akmaster]
akmaster Offline
Member
Registered: 06/11/12
Posts: 70
Loc: alaska
Thanks Greg, I will go take some pics and post them..Seems I read something in OSHA about metal clad switchgear over 600V had to be in RGS...we have a 115kV transformer stepped down to 13.8 kV...the risers and duct bank for the secondary to the metal clad switch gear is schedule 80 PVC..

The risers from the switchgear feeding out to the various transformers and electrical control rooms are pvc with RGS elbows and pvc risers...this is 13.8 and 4.16 kV..

Was thinking OSHA had requirements for circuits over 600VAC requiring steel conduit entering the metal clad gear..

Thank you,

Greg
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#210227 - 06/04/13 10:40 AM Re: NEC Article 490 [Re: akmaster]
gfretwell Offline


Member
Registered: 07/20/04
Posts: 9039
Loc: Estero,Fl,usa
That may be true. The NEC is just one piece of the puzzle.

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#210228 - 06/04/13 10:42 AM Re: NEC Article 490 [Re: akmaster]
akmaster Offline
Member
Registered: 06/11/12
Posts: 70
Loc: alaska
Does the 2005 code requre the 18" depth for RGS elbows or has that changed since then? I do not have a 2005 NEC code book..

so if anyone knows if it is the same requirement now as it was then please let me know.

thanks

Greg
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#210234 - 06/04/13 12:45 PM Re: NEC Article 490 [Re: akmaster]
HotLine1 Offline


Member
Registered: 04/03/02
Posts: 6776
Loc: Brick, NJ USA
IF the entire sweep is 18" under ground, there is no need to bond that metalic raceway. However, run a metalic riser above grade, and it must be bonded.

This has been the way it is for a longer time than I would care to admit.

BTW, all the MV jobs I have been around are in RGS above ground. 4160, 13.2, etc.


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John
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#210237 - 06/04/13 12:52 PM Re: NEC Article 490 [Re: akmaster]
akmaster Offline
Member
Registered: 06/11/12
Posts: 70
Loc: alaska
thank you hotline...

greg
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