NM in suspended ceilings

[lawrence kany]

Has NM cable ever been allowed to used in suspended ceilings of commercial buildings

 

[bth0mas20]

Im guessing it was allowed. I live in Maryland and a commercial resturant that im working on is full of nm and the ceiling used to be a drop. They have since removed the drop ceiling. The code says that you cant even have nm above a drop ceiling since it is still accesable. The inspector dosent seem to have a problem with it because it was already thier.

 

[peter d]

Has NM cable ever been allowed to used in suspended ceilings of commercial buildings

Yes, it was allowed for decades before the code change in the 2002 NEC.

 

[iwire]

Has NM cable ever been allowed to used in suspended ceilings of commercial buildings

Sure, NM is still allowed in commercial buildings although now above suspended ceilings is prohibited.

 

[stickboy1375]

It's sort of a tug of war between EMT guys and NM guys, they finally allowed NM in buildings over 3 stories, but they added the "not allowed over drop ceiling rule" which makes no sense to me by the way... :grin:

 

[peter d]

Sure, NM is still allowed in commercial buildings although now above suspended ceilings is prohibited.

Unless you work in Massachusetts.

 

[iwire]

Unless you work in Massachusetts.

Yeah.....but who works in MA? :wink:

 

[nakulak]

FWIW, I was under the impression that the reason that nm is not allowed in dropped ceilings is due to the toxic smoke development of the pvc jacket during a fire.

 

[peter d]

Yeah.....but who works in MA? :wink:

Only hacks.

 

[stickboy1375]

FWIW, I was under the impression that the reason that nm is not allowed in dropped ceilings is due to the toxic smoke development of the pvc jacket during a fire.

What about the rest of the stuff in the building? And at that point the fire is pretty out of control wouldn't you say?

 

[peter d]

What about the rest of the stuff in the building? And at that point the fire is pretty out of control wouldn't you say?

Stop introducing common sense into the argument.

 

[iwire]

FWIW, I was under the impression that the reason that nm is not allowed in dropped ceilings is due to the toxic smoke development of the pvc jacket during a fire.

That is the case with air handling ceilings.

But for non air handling ceilings it was literally a trade off for the removal of the 3 story restriction.

 

[peter d]

That is the case with air handling ceilings.

NM would be forbidden anyway because it's not plenum rated, correct?

 

[iwire]

NM would be forbidden anyway because it's not plenum rated, correct?

Kind of, but more directly 300.22(C)(1) does not list NM as a wiring method for those above ceiling spaces.

 

[peter d]

Kind of, but more directly 300.22(C)(1) does not list NM as a wiring method for those above ceiling spaces.

Thanks, I did not know there was a code that direcly addressed it, but it would make sense that NM would be forbidden.

 

[iwire]

No problem and that code section applies to any occupancy type. (Even here in MA.)

The S&Ss had return ducts.