Intent of the code question

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GerryB

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woodbridge, ct. USA
If you have a hallway in a commercial type building where 80% is a dropped ceiling but a few sections are sheetrock with recess cans, assuming nm cable is acceptable to use elsewhere could the nm be used above this hard ceiling portion? Above the hard ceiling is open just like the rest of the drop ceiling, not boxed in.
 
"within a dropped or suspended ceiling cavity"

"within a dropped or suspended ceiling cavity"

2017 NEC, 334.12 addresses this and says not permitted.
I don't know the evolution of this rule, but I'm pretty sure it was that way in '14 and maybe '11?
 
sw_ross said:
2017 NEC, 334.12 addresses this and says not permitted.
I don't know the evolution of this rule, but I'm pretty sure it was that way in '14 and maybe '11?
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LarryFine said:
He's asking about a drywall ceiling where you happen to have access from above.
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2014 wording "Exposed in dropped or suspended ceilings in other than one- and two-family and multifamily dwellings"

I think it is vague enough this is subject to interpretation.
 
LarryFine said:
He's asking about a drywall ceiling where you happen to have access from above.
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The way I'm imagining it is you draw the hallway and then draw a 2' offset from the walls. That represents the sheet rock portion. Fill in the rest of the hallway with lay-in tiles.

I'm curious as to how the sheet rock is supported. I know they make sheet rock lay-in tiles, but that doesn't seem to be what the OP is describing.
 
In the 2008 NEC, 334.12, uses not permitted it reads "exposed in dropped or suspended ceilings...".

The ceiling the original poster is describing is typical in 3 and 4 story wood frame hotels on the first floor where part of the ceiling is drop acoustic tile, and part of the ceiling is Sheetrock. They are often at different heights, with the sheetrock portions being lower and in front of the guest doors.

If I had to guess the intent of the code, it would be to prevent firefighters from hooking an axe into a burning ceiling and pulling down a bundle of energize cable on to himself.

There is no such restriction against running Comm Cable in the same ceiling, it just cannot be supported by or touching the grid. We always ran it as high to the deck as possible though for numerous reasons, firefighters poking axes into a ceiling being one of them
 
kwired said:
2014 wording "Exposed in dropped or suspended ceilings in other than one- and two-family and multifamily dwellings"

I think it is vague enough this is subject to interpretation.
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I agree, it's a little vague. By industry definition, a drop ceiling or suspended ceiling is considered to be a secondary ceiling hung below the structural ceiling. As such, it wouldn't be subject to the draft-stopping required for concealed spaces by the building code, that would create smaller spaces to limit flame and smoke spread. I have, however, seen some inspectors require draft-stopping in these types of ceilings.

Personally, if it's only a portion of the above floor area, I call it a soffit and go on with life. :cool:
 
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