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NM Cable in Crawl Spaces

R

Robert Ellenberg

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Joined
Feb 6, 2010
Messages
210
Location
Louisiana
The 2008 NEC requires the following: “In Unfinished Basements and Crawl Spaces. Where cable is run at angles with joists in unfinished basements and crawl spaces, it shall be permissible to secure cables not smaller than two 6 AWG or three 8 AWG conductors directly to the lower edges of the joists. Smaller cables shall be run either through bored holes in joists or on running boards.”

This was previously true in unfinished basements but the 2008 edition adds crawlspaces. My question is how do you take wiring from one side of a girder to the other (it is not a dropped girder but the joists butt into it). The code makes no provision for drilling holes in girders (and it shouldn't). Can you tack a small piece of wood on the bottom of the girder (a short section of running board), run your cables parallel to or through holes in the joists on one side of the girder, drop the wire down and tack it to the short section of running board and then continue back up on the other side of the girder?

Would appreciate comments on whether or not you would consider this compliant and/or any other way to meet this provision.
 
If you think it's necessary. IMO the intent of the running board is to secure the cable in a manner to prevent the likelihood of using the exposed cable to hang stuff though it could encourage people to do so if it were routed inside a conduit at angles to the joist; still it protects the cable from damage.

Francis
 
Couldn't plastic zip ties be used to attach / secure the conductors along the girder?

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ie the crawl sppace "accessible", like is someone going to get in there and be doing something other than a belly crawl? plastic zip ties, yuk. wouldn't staples work just as well ?
 
2008 NEC 334.15 © Is it a wooden girder or steel? There would be no reason prohibiting you from stapling directly to the girder if it is wood if it is metal follow contour of beam and staple on both sides of floor joists. 2008 NEC 334.15 (A) to follow surface. The running board only provide a surface to follow, the girder would provide a surface to follow.
 
Wood girder and yes, you can staple the crossing wires directly to the bottom of it where they cross. I was looking as to how to comply with both the intent and the "letter" of the code as I believe the NEC requirement I am referring to specifically prohibits stapeling to the edge of framing members, which stapling to the bottom of the girder would be.
 
Robert Ellenberg said:
Wood girder and yes, you can staple the crossing wires directly to the bottom of it where they cross. I was looking as to how to comply with both the intent and the "letter" of the code as I believe the NEC requirement I am referring to specifically prohibits stapeling to the edge of framing members, which stapling to the bottom of the girder would be.
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I gave you the section that you are referencing. 300(D) tells you if the wire is running parallel with the framing member there needs to be a minimum of 1 and 1/4 inches from the edge. The way that I envision what you are doing is when crossing under the beam you would be perpendicular so no nail or screw damage would be possible. It is no different than running the wire down the middle of a running board that is crossing the floor joist, the wire is still exsposed to the open space.
 
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