2011 NEC 334.12(A)(2)

[construct]

Says that NM, NMC, and NMS cables are not allowed in dropped or suspended ceilings in other than one and two and multifamily dwellings. I'm trying to find some clarity between "dropped" and "suspended". I think that a suspended ceiling is a drop ceiling, but a drop ceiling is not necessarily a suspended ceiling. Some manufacturers refer to their suspended ceilings as drop ceilings.

My scenario is that I'm looking at a 4 story hotel. The bottom of the floor joists above are sheetrocked, but in the bathrooms, the ceiling is then dropped another 1.5 ft, framed and sheetrocked and romex used in the wiring method. I think this complies with 334.10(3) in that it is concealed behind a thermal barrier of material with a 15 minute finish rating.

Thoughts and input would be appreciated. :?

 

[Dennis Alwon]

I think this is a hard one to answer. I have always thought if the ceiling were sheetrocked then it was a non issue. I am not sure of the intent but if you think about it why would it matter if the ceiling is dropped if it has sheetrock on it. The dropped area must be fire blocked so I don't see the issue. I assumed they used the term loosely so it is hard to know intent

 

[construct]

I have always thought if the ceiling were sheetrocked then it was a non issue. I am not sure of the intent but if you think about it why would it matter if the ceiling is dropped if it has sheetrock on it.

This is the way I see it also. IMO it would comply with 334.10(3). I just wondered what others thought.

Thanks Dennis.

 

[iwire]

My understanding is that the restriction has to do with the cable getting damaged by other trades working in the suspended ceiling.

If that is the case it should only apply to ceilings with lift out panels.

 

[JFletcher]

a drop or suspended ceiling is removable tiles of some sort. Having a 1.5' elevation change but it's all sheetrock/hard ceiling is not a drop ceiling. I think the install as described is compliant.

 

[don_resqcapt19]

My understanding is that the restriction has to do with the cable getting damaged by other trades working in the suspended ceiling.

If that is the case it should only apply to ceilings with lift out panels.

And my understanding the restriction was nothing more than being part of a "trade-off" to get rid of the 3 story rule that was in previous codes.

 

[iwire]

And my understanding the restriction was nothing more than being part of a "trade-off" to get rid of the 3 story rule that was in previous codes.

I don't doubt you in the least that was the driving force but I thought the substantiation mentioned damage from other trades.

 

[Smart $]

... in the bathrooms, the ceiling is then dropped another 1.5 ft, framed and sheetrocked...

I believe that is a dropped ceiling per architectural definition. The sheetrocked bottom of joists above would be the structural ceiling.

 

[George Stolz]

My understanding is that the restriction has to do with the cable getting damaged by other trades working in the suspended ceiling.

If that is the case it should only apply to ceilings with lift out panels.

The definition of "concealed" corroborates your sentiment; I don't have to damage ceiling tiles to access wiring above it, but I would have to damage drywall of a dropped ceiling to access it.

Sounds like the hotel is legal with the hard lid, but would be a violation with tiles.

 

[ActionDave]

My understanding is that the restriction has to do with the cable getting damaged by other trades working in the suspended ceiling.

If that is the case it should only apply to ceilings with lift out panels.

The definition of "concealed" corroborates your sentiment; I don't have to damage ceiling tiles to access wiring above it, but I would have to damage drywall of a dropped ceiling to access it.

Sounds like the hotel is legal with the hard lid, but would be a violation with tiles.

And the definition of "exposed" pretty much seals the deal.

Exposed (as applied to wiring methods). On or attached
to the surface or behind panels designed to allow access.

Behind a hard lid is ok.

 

[construct]

I agree with the concensus that it is a compliant installation. I appreciate you all weighing in with your take.

Thanks to all