Wires perpendicular to joists in basement

[Stevenfyeager]

We can’t run wires perpendicular on bottom of joists in basements (or crawl spaces) unless it is #6 or bigger. This is what the inspectors have been telling us. But what if there is a suspended ceiling? Is it ok then ?

 

[kwired]

Good question.

New construction I always do the initial rough in drilled in. Additional wiring between lights after the ceiling is hung is usually attached to bottom of joists though when it runs perpendicular to the joist.

 

[rc/retired]

Unfortunately there's no exception for suspended ceilings

 

[infinity]

The restriction is for unfinished basements. If there is a finished room with a hung ceiling there is no restriction on running on the underside of the joists.

 

[kwired]

The restriction is for unfinished basements. If there is a finished room with a hung ceiling there is no restriction on running on the underside of the joists.

They did add crawlspaces in one of the more recent NEC editions. (recent meaning maybe up to 15 years ago, time flies...)

 

[James L]

It is absolutely acceptable to run perpendicular to the joists - UNDER joists - in a grid ceiling

334.12(a)2 permits it "within" grid ceilings

335.15(c) states that in UNFINISHED basements it cannot be under joists if smaller than #6

That prohibition for unfinished basements doesn't apply to a finished grid ceiling

 

[Stevenfyeager]

Thank you so much ! I had my workers run it perpendicular this morning when they called and asked me. Was hoping that was correct !

 

[rc/retired]

Yeah, dang. I had a dumb ass attack

 

[Fred B]

Is this a 1 or 2 family dwelling? If yes then @James L statement is correct, if not then it is prohibited to run NM under a drop ceiling grid.

 

[farmantenna]

I disagree. 334-15 Exposed work install per A-C
definition of exposed Art100
can you run NM perp to joists if exposed?

 

[infinity]

I disagree. 334-15 Exposed work install per A-C
definition of exposed Art100
can you run NM perp to joists if exposed?

Not unless it's 6-2 or 8-3 or larger. The OP is asking about running under the joists above a drop ceiling which is permitted for any size NM cable.

 

[kwired]

Is this a 1 or 2 family dwelling? If yes then @James L statement is correct, if not then it is prohibited to run NM under a drop ceiling grid.

Can't run NM above either

 

[GeorgeB]

Can't run NM above either

I wanted to say that, too ... under is between the ceiling and floor?

 

[James L]

Can't run NM above either

That tricky distinction between above, under and within

 

[James L]

I wanted to say that, too ... under is between the ceiling and floor?

Like when people say "under counter lights"

I be like....under the counter would be the lower cabinet

 

[kwired]

Like when people say "under counter lights"

I be like....under the counter would be the lower cabinet

I hear that a lot as well.

As far as I'm concerned as long as we are within a strong influence of Earth's gravitational effects, down, under, below, etc. is the direction of pull of Earth's gravity on all the smaller objects. Even if you are standing on your head.

 

[retirede]

Like when people say "under counter lights"

I be like....under the counter would be the lower cabinet

I can’t say I’ve ever heard that. Always “under cabinet” lights.

 

[augie47]

One of those situations where one has to be careful what is said.
I have had inspections where the NM is on the bottom of the joists in an unfinished basement and I have mistakenly said "if it had a drop ceiling it would have been ok"... only to return to find a suspended ceiling in rooms that had no wall receptacles whatsoever,... now what do we have ?

 

[LarryFine]

One of those situations where one has to be careful what is said.
I have had inspections where the NM is on the bottom of the joists in an unfinished basement and I have mistakenly said "if it had a drop ceiling it would have been ok"... only to return to find a suspended ceiling in rooms that had no wall receptacles whatsoever,... now what do we have ?

"Well, I didn't say 'only'!"

 

[infinity]

One of those situations where one has to be careful what is said.
I have had inspections where the NM is on the bottom of the joists in an unfinished basement and I have mistakenly said "if it had a drop ceiling it would have been ok"... only to return to find a suspended ceiling in rooms that had no wall receptacles whatsoever,... now what do we have ?

What if you had a finished basement with open joists above but no drop ceiling?