stapling wires on bottom of joists in crawlspace

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Stevenfyeager

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United States, Indiana
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electrical contractor
A county elec inspector failed a friend of mine electrician of 20 years for stapling cables on bottom of floor joists in a crawlspace. He is making him install wood strips and zip ties. I know local building codes sometimes trump NEC. Is this in NEC ? I forgot to ask him for the reason the inspector gave. I know they don't like basement joist stapling, but have you ever heard of crawlspace stapling ?
Thank you.
 
I recall there was a code change a few cycles ago that changed the way crawl space wiring was done.
What code are you on?
 
Stevenfyeager said:
A county elec inspector failed a friend of mine electrician of 20 years for stapling cables on bottom of floor joists in a crawlspace. He is making him install wood strips and zip ties. I know local building codes sometimes trump NEC. Is this in NEC ? I forgot to ask him for the reason the inspector gave. I know they don't like basement joist stapling, but have you ever heard of crawlspace stapling ?
Thank you.
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Some states have amended that article. May want to check yours.
 
Thank you, I see that in 334.15 in the 2017 NEC. I was caught off guard ! I'm sure he wants "running boards" with the cables zip tied to them. Why is it ok to run cables on top of attic joists with no "running boards" ? What's the difference ? I don't understand.
 
Stevenfyeager said:
Thank you, I see that in 334.15 in the 2017 NEC. I was caught off guard ! I'm sure he wants "running boards" with the cables zip tied to them. Why is it ok to run cables on top of attic joists with no "running boards" ? What's the difference ? I don't understand.
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The cables in an attic would have to be "guarded" by running boards or similar if the wiring is within 6' of the scuttle hole. The reason they don't want cables stapled on floor joists is to prevent people from using it as a "clothes line" or hanging anything on it, like rakes, shovels, etc. I'm guessing the reason larger wires are allowed is they wouldn't swag or pull down as easily as smaller cables.

In my area, they will allow stapling on the bottom of joists in a crawl space if the space is no more than 4' in height.
 
Note that as long as the cable is running parallel to the joist the code is perfectly happy with stapled cables except in the attic near the scuttle where they are likely to be walked on.
 
Is it permissible to stable NM to the bottom of the roof joist in an attic w/out installing running boards (the NM running perpendicular to the framing)? I didn't see that specifically mentioned in the sections mentioned but didn't do extra reading.
 
Thanks. I am still not understanding the reason for not allowing stapling cables smaller than #8 on bottom of crawl space floor joists but ok to install perpendicular to ceiling joists in attics (>6' away from access). A cable would sag even more in an attic because the distance is usually 22 1/2 inches between, but in a crawl, only 14 1/2 " between supports. ??? And my second question is: the inspector said the crawl space cables either need to be drilled or use a 'running board'....but if I drill, (as he says we have to), that still leaves almost the same sagging distance of 14 1/2 " between joists. ?? Same sagging. ?
 
You don't have to drill. If you square off your runs then you can keep everything to the outside wall or on the beams between load points on the house. If not then you either drill or use a running board.

The reason this was put into code was because nobody could determine when a crawl space was a crawl space and not a basement. Fortunately, NC deleted this change from years ago..
 
Stevenfyeager said:
Thanks. I am still not understanding the reason for not allowing stapling cables smaller than #8 on bottom of crawl space floor joists but ok to install perpendicular to ceiling joists in attics (>6' away from access). A cable would sag even more in an attic because the distance is usually 22 1/2 inches between, but in a crawl, only 14 1/2 " between supports. ??? And my second question is: the inspector said the crawl space cables either need to be drilled or use a 'running board'....but if I drill, (as he says we have to), that still leaves almost the same sagging distance of 14 1/2 " between joists. ?? Same sagging. ?
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The issue is not sagging, but rather being accidentally hit by something close to ceiling height, or deliberately used to hang things (clothes from dryer, etc.)
I think the idea is that #8 and larger cable is not as vulnerable to damage.

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