NM cable above residential drop ceiling

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nizak

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Can NM cable be stapled to the underside of floor joists above a drop ceiling? I've inherited a job started by a handyman who has installed all the home runs directly to the bottom of the floor joists. There's about a dozen cables run the entire basement length ( approx 60' to load center).

I've always made it a practice to drill the joists even when there's a drop ceiling.

Could it be flagged by the AHJ for "subject to physical damage?

There's about 2"of clearance between the grid work and the joists. Just enough space for a hanger eye and an inch or so of twisted wire.

Thanks
 
I was of the opinion that it could be stapled to the underside of the joists if it's above the hung ceiling but I now believe that even with the ceiling it would need to be on running boards.
 
infinity said:
I was of the opinion that it could be stapled to the underside of the joists if it's above the hung ceiling but I now believe that even with the ceiling it would need to be on running boards.
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Why is that? I see the lay in ceiling changing the unfinished basement to a finished basement and when it is finished 334.15(C) would not apply.
 
don_resqcapt19 said:
Why is that? I see the lay in ceiling changing the unfinished basement to a finished basement and when it is finished 334.15(C) would not apply.
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The definition: Exposed (as applied to wiring methods) on or attached to the surface or behind panels designed to allow access.
 
If you can't do it in a crawl space, one would think you can't do it above a drop ceiling. Personally, in those two cases, I don't really see it as a hazard, it's more about not letting someone grab the wire for support or hang stuff from it. I supose you can imagine someone who removed a ceiling tile to do something and was on a ladder and loses their balance and reaches up to grab the wire to not fall. You can also just tack up some boards and move the wires over there of use someting fancy like this: http://www.aifittings.com/catalog/n...rts/cableway-cable-runway-support-system/T205
 
jaggedben said:
So that makes 334.15 apply in general, but 334.15(C) still doesn't apply as Don said, if the basement is finished.
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I agree with this. It's helpful to nail down what constitutes finished.

I finished my sister's basement about 12 years ago, and only sheetrocked the walls. The ceiling remained open, and I painted it all a rust color for a loft look.

I didn't run any Romex under the joists, but had I done that it would be ok because it's a finished basement. The only thing it's missing is ceiling grid
 
infinity said:
The definition: Exposed (as applied to wiring methods) on or attached to the surface or behind panels designed to allow access.
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I see two different rules in play here, and the one that requires the running boards only applies to unfinished basements. It does not say anyting about the NM being exposed. I stand by my statement that where the basement has a drop ceiling, it is a finished basement, and the requirement for running boards in 334.15(C) does not apply. The idea of the NM being exposed or not, does not enter into this first level subdivision.
 
Here's a few more code sections.

First the Article 100 definition of exposed fits this installation as it's "behind panels designed to allow access."

334.15 further defines exposed work when related to NM cable. 334.15(A) requires that it either follows the surface of the building or be installed on running boards. Stapled on the underside of the joists perpenduclar to the hoists from one to the next is not following the surface of the building finish. Stapled to the side of the joist would be following the surface of the building.

334.15 Exposed Work.
In exposed work, except as provided in 300.11(B), cable shall be installed as specified in 334.15(A) through (C).
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334.15(A) To Follow Surface.
Cable shall closely follow the surface of the building finish or of running boards.
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I had the same thing happen to me about a year ago. I got flagged for the same thing. However the AHJ was a cool guy and went to the code book and admitted he was wrong and you could staple to the bottom of the joists above a drop ceiling.


Sent from my iPhone using Tapatalk Pro
 
sparky1118 said:
I had the same thing happen to me about a year ago. I got flagged for the same thing. However the AHJ was a cool guy and went to the code book and admitted he was wrong and you could staple to the bottom of the joists above a drop ceiling.
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He was right the first time. 334.12(A)(2) even states "Exposed within a dropped or suspended ceiling cavity"
 
infinity said:
He was right the first time. 334.12(A)(2) even states "Exposed within a dropped or suspended ceiling cavity"
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But all that is irrelevant if the basement isn't 'unfinished.'

I think your argument rests on the notion that a drop ceiling isn't a finish, or isn't a proper one. Which is an interpretation, since AFAIK 'finished' isn't defined.
 
jaggedben said:
But all that is irrelevant if the basement isn't 'unfinished.'

I think your argument rests on the notion that a drop ceiling isn't a finish, or isn't a proper one. Which is an interpretation, since AFAIK 'finished' isn't defined.
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It doesn't say anything about finished or unfinished it just says Exposed within a dropped or suspended ceiling cavity.
 
jaggedben said:
I see where you're quoting from now but you snipped off "in other than one and two-family and multifamily dwellings." C'mon.
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I left that off intentionally because it is not relevant to my point which is that the NEC clears says exposed within a dropped ceiling when referring to NM cable above the ceiling.
 
The entirety of 334.12(A)(2) is irrelevant.

Your logic that 'follow the surface of the building finish or running boards' prohibits stapling to the bottom of joists applies equally to boring holes through joists. But nobody thinks boring holes through joists is prohibited. Therefore stapling to the bottom must also be following the surface.

It all comes down to whether a drop ceiling is a 'finish'.
 
(C) only applies where the basement is "unfinished". There is nothing about exposed in (C). The only issue here is if a lay in ceiling is a finish or not. I see it as a finish and see (C) as clearly permitting cables of any size to be installed on the bottom of the joists.

Remember the whole concept of this rule is completely flawed. The concept is so that you don't use the cables to hang things on, but when you install them through bored holes, they work much better for hanging things on than they do where they are ran on the bottom with a staple ever third joist.

If (A) applies everywhere, how can we run NM on the top of ceiling joists or the bottom of rafters in an attic?
 
don_resqcapt19 said:
(C) only applies where the basement is "unfinished". There is nothing about exposed in (C). The only issue here is if a lay in ceiling is a finish or not. I see it as a finish and see (C) as clearly permitting cables of any size to be installed on the bottom of the joists.
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I wouldn't say that a drop ceiling alone constitutes finishing the basement; if the walls and the floor are still unfinished, then IMO the basement is still unfinished. In which case 334.15(C) would still apply, unless you say that above the drop ceiling is no longer part of the unfinished basement. Which is a plausible interpretation.

Conversely, if the basement is finished, that would mean 334.15(C) wouldn't apply at all. Therefore it wouldn't actually grant any permissions, it would just be irrelevant.

don_resqcapt19 said:
If (A) applies everywhere, how can we run NM on the top of ceiling joists or the bottom of rafters in an attic?
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That is an excellent question, and suggests to me that 334.15(A) is just flawed. What sort of install is it trying to prohibit, and how can it be interpreted in a way that doesn't prohibit running NM cable through bored holes in exposed joists?

Cheers, Wayne
 
wwhitney said:
I wouldn't say that a drop ceiling alone constitutes finishing the basement; if the walls and the floor are still unfinished, then IMO the basement is still unfinished. In which case 334.15(C) would still apply, unless you say that above the drop ceiling is no longer part of the unfinished basement. Which is a plausible interpretation.

Conversely, if the basement is finished, that would mean 334.15(C) wouldn't apply at all. Therefore it wouldn't actually grant any permissions, it would just be irrelevant.


That is an excellent question, and suggests to me that 334.15(A) is just flawed. What sort of install is it trying to prohibit, and how can it be interpreted in a way that doesn't prohibit running NM cable through bored holes in exposed joists?

Cheers, Wayne
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How finished does a wall have to be to be finished? What if there is a drop ceiling and drywall on the wall, but no tape and joint compound? Is the basement unfinished?
 
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