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#12926 - 08/21/02 04:11 PM Opinion needed
Jim M Offline

Registered: 08/10/01
Posts: 453
Loc: Chestertown, MD, USA
This was posted on a DIY site. I don't see how Article 312 would apply to a sleeve for NM-B running to a surface mounted device ie switch or receptacle. Your thoughts?

We commonly 'sleeve' romex NM-B cable from a suface mounted wall box ...and it extends up into a joist space...and does not penetrate any of the structure.This saves us from installing a splice box up there!

The conduit is generally a straight piece and extends up into the joist space,and MUST have a protective bushing on that far end.

A complete conduit system is defined as one with enclosures etc at each end.

A 24" short nipple between two enclosures ,and no longer than 24" is permotted to be filled at 60% of its it is apart of a complete system.
This would require a trade size conduit of no less than 3/4" for a 12-2G NM-B cable.

Your installation is not a complete system...and the 1/2" conduit is fine,[I prefer 3/4" for this ] if between 18" and not longer than 10ft..and if it is also secured at the far end...if the NM-B was installed without trauma...a bushing is installed and the opening sealed as per 312-5.c.d...and the cable is stapled within 12" of the exit point in that joist space...

I have always used a bushing and properly secured the cable, but don't see the purpose of the raceway seal. I don't know how the moderator thinks that this Article would apply as this is not entering a cabinet, cutout or meter socket.

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#12927 - 08/21/02 05:35 PM Re: Opinion needed
ElectricAL Offline

Registered: 10/10/01
Posts: 615
Loc: Minneapolis, MN USA
I agree with you, Jim. Seems to me that 300.4 is the appropriate reference.

Al Hildenbrand


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