Romex above fire rated drop ceiling....

[chevyx92]

Is this allowed by code even though NM isn't allowed above a suspended ceiling in a commercial setting?

 

[augie47]

IMO, it is still not allowed if it is a dropped or suspended ceiling.

 

[mwm1752]

Is your dropped ceiling accessible?

 

[gadfly56]

Is this allowed by code even though NM isn't allowed above a suspended ceiling in a commercial setting?

Do you mean, for example, in a residential setting, where someone adds a drop ceiling in a basement?

 

[Dennis Alwon]

Do you mean, for example, in a residential setting, where someone adds a drop ceiling in a basement?

The op stated commercial. It is allowed in residential as you described. Look at 334.12(A)(2)

 

[gadfly56]

The op stated commercial. It is allowed in residential as you described. Look at 334.12(A)(2)

I read the OP as ambiguous on the matter of the type of space. The way the question is worded, to me, asks whether NM is allowed above any fire rated drop ceiling (whatever that is, exactly) even though it isn't allowed, for example, in a commercial setting, without directly saying the fire rated drop ceiling is in a commercial setting.

I could, of course, be reading too much into it, but ambiguity is not your friend when asking code questions.

 

[shortcircuit2]

IMO, it is still not allowed if it is a dropped or suspended ceiling.

Please tell us why you think it should not be allowed?

 

[Smart $]

I read the OP as ambiguous on the matter of the type of space. The way the question is worded, to me, asks whether NM is allowed above any fire rated drop ceiling (whatever that is, exactly) even though it isn't allowed, for example, in a commercial setting, without directly saying the fire rated drop ceiling is in a commercial setting.

I could, of course, be reading too much into it, but ambiguity is not your friend when asking code questions.

I agree the question is ambiguous... but quite simply, NM isn't permitted to be run exposed in dropped or suspended ceilings in other than dwellings.

In dwellings, I believe it is permitted regardless of whether the suspended ceiling is fire-rated or not.

 

[augie47]

Please tell us why you think it should not be allowed?

334.12(A)(2)

 

[chevyx92]

Do you mean, for example, in a residential setting, where someone adds a drop ceiling in a basement?

I'm talking about commercial setting.

 

[mgookin]

Were you thinking that it's not allowed because of fire protection issues?

Fire rating something that is not allowed does not make it allowed. If that were the case, the code would say only fire rated NM is allowed, and that's not the case.

 

[mwm1752]

Residential occupancies are not just 1 & 2 family dwellings- hotels, condos, townhomes ect -- Nm uses are not permited in accessible dropped ceiling are based upon types of construction. Types III, IV, & V ( 3,4,5) are allowed to use NM as long as the install is concealed within walls, floors & ceilings ( a dropp ceiling inaccessible makes the installation concealed) -- You may use NM in commercial buildings as long other sections of the NEC do not prohobit the install (Places of assemblies, Hazardous Locations) to name a few. So wheather the building is residential or commercial has little bearing when it comes to dropped ceilings.

 

[Smart $]

Residential occupancies are not just 1 & 2 family dwellings- hotels, condos, townhomes ect -- Nm uses are not permited in accessible dropped ceiling are based upon types of construction. Types III, IV, & V ( 3,4,5) are allowed to use NM as long as the install is concealed within walls, floors & ceilings ( a dropp ceiling inaccessible makes the installation concealed) -- You may use NM in commercial buildings as long other sections of the NEC do not prohobit the install (Places of assemblies, Hazardous Locations) to name a few. So wheather the building is residential or commercial has little bearing when it comes to dropped ceilings.

I think not...

334.12 Uses Not Permitted.


(A) Types NM, NMC, and NMS. Types NM, NMC, and
NMS cables shall not be permitted as follows:

...

(2) Exposed in dropped or suspended ceilings in other
than one- and two-family and multifamily dwellings

NEC appears to consider it exposed and not permitted in other than dwelling units, including hotels.

 

[mwm1752]

I think not...


NEC appears to consider it exposed and not permitted in other than dwelling units, including hotels.

I disagree NEC 2011 commentary
Section 334.12(A)(2) prohibits nonmetallic-sheathed cables installed as exposed in the space above accessible hung ceilings. This requirement does not affect dwelling-type occupancies.
The term exposed, as used in this requirement, closely follows the definition of exposed (as applied to wiring methods) found in Article 100, which states ?on or attached to the surface or behind panels designed to allow access.?
For example, cables installed above a dropped gypsum board ceiling or dropped gypsum board soffit would not be considered exposed cable, provided the area above the ceiling is not accessible (does not have removable tiles or does not contain an access panel).

The covered inaccessible dropped ceiling or soffit according to the commentary "would not consider the cable exposed" and the permitted application use of nm include type III,IV & V constuction. Any hotel built under any of these types of constuction can have nm as a wiring method as long as it is not install exposed in a drop ceiling. If a cable is not considered exposed as per commentary then it must be considered concealed.

 

[david]

Residential occupancies are not just 1 & 2 family dwellings- hotels, condos, townhomes ect -- Nm uses are not permited in accessible dropped ceiling are based upon types of construction.

This statement is not correct in relationship to this discussion as smart pointed out in his comment

I think not...


NEC appears to consider it exposed and not permitted in other than dwelling units, including hotels.

 

[Smart $]

I disagree NEC 2011 commentary
... If a cable is not considered exposed as per commentary then it must be considered concealed.

If you are referring to Handbook commentary, we both know it's not enforceable and not to be considered an official interpretation. However, that may well be the intent.

However, if we look at the Code stipulation from a literal and technical perspective, it is poorly worded to begin with. It states, "Exposed in dropped or suspended ceilings..." With ceiling not defined in Code, we refer to the official dictionary for the definition of "the inside surface at the top of a room". Without getting into the physics of a surface, it amounts to you can't install anything in a ceiling. With that said, we must assume the intended target is in the ceiling cavity, i.e. the space above the suspended or dropped ceiling [surface] and below the structural boundary above.

From there we have to integrate 300.11 into our interpretation. In short, we cannot secure or support cable to or by the ceiling assembly. That leaves only securing to or supporting from the structure above.

Since this is a literal and technical interpretation, to consider the installation as exposed or concealed, we must have a frame of reference to make the determination. We have already determined the cable will be secured to or supported by the structure above, i.e. "on or attached to the surface" as in the definition of exposed. Nothing in the definition of exposed states the frame of reference is the apparent or structural boundaries.

I leave the final conclusion to anyone reading this...

 

[mwm1752]

If you are referring to Handbook commentary, we both know it's not enforceable and not to be considered an official interpretation. However, that may well be the intent.
With ceiling not defined in Code, we refer to the official dictionary for the definition of "the inside surface at the top of a room".
I leave the final conclusion to anyone reading this...

I find it interesting that you refer to an official dictionary not part of the code or enforceable to conclude your point. Lets use NEC definitions;

Concealed. Rendered inaccessible by the structure or finish of the building. Wires in concealed raceways are considered concealed, even though they may become accessible by withdrawing them.
Is not drywall a finish or an inside surface within a room? Please don't talk about paint or texture.
Even though handbook commentary is not code , the intent is to help with the poorly chosen wording in the code for a reasonable interpretation, We can discuss the interpretation of how the statement appears but to ignore the commentary in text seems a bit stubborn (certainly a right). I believe the NEC definitions of concealed & exposed along with the "the inside surface at the top of a room" provide evidence a soffit or drop ceiling with a finish cover over nm that cannot be accessed unless it is removed/destroyed meet the requirements of 334.10 (2) & (3).

 

[mwm1752]

This statement is not correct in relationship to this discussion as smart pointed out in his comment

The comment was to address the confusion over firerated assemblies and commercial installations -- Smart is the one to use the quote in an answer. as for his comments of I think not -- does it refer to not allowing the use of NM in commercial buildings? Hotels which are included in the residential group per the IBC? Or is it just he concludes that NM is considered exposed when installed behind sheetrock. Maybe you can clarify

 

[Smart $]

I find it interesting that you refer to an official dictionary not part of the code or enforceable to conclude your point. ...

You can find this statement in many NFPA documents:

Webster?s Collegiate Dictionary, 11th edition, shall be the source for the ordinarily accepted meaning.

For example: http://www.nfpa.org/~/media/files/c... directory and forms/tc_stylemanual_07-04.pdf

You are entitled to your interpretation. The only one that counts is the AHJ's, though even theirs can be challenged if so inclined... :happyyes:

 

[mgookin]

When a code defines a word, term or phrase, the definition in the code shall be used. Absent a definition in the code, then you defer to a dictionary.