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#101209 - 02/22/07 06:48 AM 334.10(3)  
shortcircuit  Offline
Joined: Jun 2004
Posts: 608
I have to admit I am still confused and can not get a straight answer on the code language requiring NM cable in non-dwellings to be within a 15 min rated concealment.

This appears to prohibit NM if installed without a wall or ceiling covering with a 15 minute fire rating.

Wouldn't this rule prohibit it also above a drop ceiling which has no fire rating to the assembly? Any thoughts?


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#101210 - 02/22/07 06:54 AM Re: 334.10(3)  
Roger  Offline
Joined: May 2002
Posts: 1,716
Shortcircuit, it is specifically prohibited above drop ceilings in other than one- and two-family and multifamily dwellings so the 15 min finish rating wouldn't directly come into play.

See 334.12(A)(2)

Does MA have an exception to this rule?


[This message has been edited by Roger (edited 02-22-2007).]

#101211 - 02/22/07 07:11 AM Re: 334.10(3)  
shortcircuit  Offline
Joined: Jun 2004
Posts: 608
Hello Roger,

Massachusetts does have an exception to the drop ceiling rule...334.12(A)(2) which allows NM above drop ceilings with some restriction.

But 334.10(3) is not ammended and this seems to be a conflict to me.

Still confused...?


#101212 - 02/22/07 07:45 AM Re: 334.10(3)  
SteveFehr  Offline
Joined: Mar 2005
Posts: 1,213
Chesapeake, VA
shortcircuit, 334.10 does not prohibit use of NM in commercial applications, it merely specifically permits it. It's not until 334.12(A)(1) where uses not permitted in 334.10 are prohibited.

Has 334.12(A)(1) been ammended in MA or only 334.12(A)(2)? Spirit of the law would say if they ammended 334.12(A)(2) to allow it, they imply an exception to 334.12(A)(1) as well... How is the ammendment worded? Does it mean you can install above drop ceilings, but they need to be 15-minute fire rated?

[This message has been edited by SteveFehr (edited 02-22-2007).]

#101213 - 02/22/07 08:43 AM Re: 334.10(3)  
shortcircuit  Offline
Joined: Jun 2004
Posts: 608

334.10 does not prohit NM in commercial installation as long as it is installed behind a 15 minute fire rated I interpret it to say...right?

But 334.12(A)(2) is ammended in Mass. does allow NM above drop ceilings in commercial installations as long as it closely follows the building framing or connects to lumineers as permitted in 334.30(B)(2)

334.10(3) and 334.12(A)(2) seem to be in conflict if the drop ceiling is not fire rated...which most are not.

Do I make sence?


#101214 - 02/22/07 11:32 AM Re: 334.10(3)  
George Little  Offline
Joined: Jan 2004
Posts: 1,489
Michigan USA
Now that you've open that can of worms riddle me this:

334.12(A)(2) {'05 NEC} or 334.12(A)(1) {'02 NEC} talk about "open runs" does anyone have a definition of "open runs"? Are they talking about NM cable pulled through the trusses above the ceiling? Are they talking about drops for fixtures wips? And secondly- what kind of a drop ceiling are we talking about? Is it a drop or suspended ceiling with removable panel that may or may not be fired rated? or is it a dropped drywall ceiling some sometimes caled a Z spline ceiling?

George Little

#101215 - 02/22/07 12:41 PM Re: 334.10(3)  
SteveFehr  Offline
Joined: Mar 2005
Posts: 1,213
Chesapeake, VA
I believe 334.10(3) still requires the drop ceiling be rated for 15 minutes. By the sounds of it, the MA exception doesn't change that, it merely allows NM to be installed where it was explicitely prohibted by a separate item.

#101216 - 02/22/07 01:40 PM Re: 334.10(3)  
ShockMe77  Offline
Joined: Jun 2005
Posts: 821
Rahway, New Jersey
I was always under the impresssion that NM was ok in a commercial/ suspeneded ceiling as long as the space above the ceiling wasn't plenum-rated.

#101217 - 02/22/07 02:45 PM Re: 334.10(3)  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,123
I am not a fire code wizard but I did come to understand that some suspended ceilings are fire rated assemblies.
As for the "open run" question, that still will not relieve the installer from the securing and "closely follow building finish" rules so whips are out as a general rule. I suppose that will start the whip to the disposal/water heater thing again.

Greg Fretwell

#101218 - 02/22/07 08:14 PM Re: 334.10(3)  
shortcircuit  Offline
Joined: Jun 2004
Posts: 608
Thanx for the replies guys...

George Little...Hello...the ceilings I'm refering to would be suspended grid type with removeable 2x4 tiles.

"Open runs" of cable to me would imply not concealed or not accessible. A removeable ceiling tile in a suspended ceiling would make the wiring above an "open run" in my opinion. are you...this is the part I not sure of...does a typical 2x4 drop ceiling have a 15-minute finish fire rating? If so then NM would be allowed above in Massachusetts.


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