History of 334.12 prohibition of NM above suspended ceilings in commercial space?

Status
Not open for further replies.
H

htroberts

Member
Art. 334.12 (a) (2) says NM is not permitted exposed in dropped or suspended ceilings in other than one- and two-family and multifamily dwellings.

How long has this been in the code?

We’re not sure when it was installed, but have found some romex above a non-plenum dropped ceiling, and need to know if it has ever been legal. The building was built in 1986.
 
Last edited:
It was part of the changes made when the 3 story limitation was removed from the code. This happened in the 2002 code. The changes were hotly debated, and I believe the addition of the above ceiling restriction was just part of the negotiations to get enough votes to remove the 3 story limit.
 
don_resqcapt19 said:
It was part of the changes made when the 3 story limitation was removed from the code. This happened in the 2002 code. The changes were hotly debated, and I believe the addition of the above ceiling restriction was just part of the negotiations to get enough votes to remove the 3 story limit.
Click to expand...

What!!! I am shocked!

Truely shocked, I tell you.

I had no idea that back room politics were a part of the code making process........
 
jaggedben said:
Ok I'll bite...
What was the 3-story limit?
Click to expand...
Basically a four story building couldn't use NM cable, possibly did not include a single family dwelling, can't remember anymore.

Now you can still run NM in many different places but outside of single family dwellings usually needs to be behind at least a 15 minute finish.


Add: just looked in 1996 NEC, was limited to three floors in all dwellings also. Three floors meant where more then 50% of the level was above grade, so a "shallow basement" would have counted as one floor above grade.
 
Used to run a lot of NM cable in non dwellings, now you do need to pay more close attention to where you can use it, though it can still be used in a lot of places, just not all throughout the facility.

Many just use AC or MC cable to avoid getting something wrong in this area.
 
don_resqcapt19 said:
It was part of the changes made when the 3 story limitation was removed from the code. This happened in the 2002 code. The changes were hotly debated, and I believe the addition of the above ceiling restriction was just part of the negotiations to get enough votes to remove the 3 story limit.
Click to expand...

Code changes can come down to simple horse trading? If that's true then that is flat out disgusting.
 
Hey... "Its A Real World Out There"... my instructor used to say to me.

Also, humans have been "trading" for thousands of years.

Here is Massachusetts amendment to Romex above dropped ceilings...

334.12(A)(2). Revise to read as follows:
(2) In dropped or suspended ceilings in other than one- and two-family and multifamily dwellings, unless run so as to closely follow the surface of framing members, running boards, or the equivalent, or unless connected to luminaries or other pieces of electrical equipment in accordance with 334.30(B)(2).

Here in Massachusetts we also have the following amendment on Romex use...

334.10. Amend (3) and insert an exception to read as follows:
(3) Other structures permitted to be of Types III, IV, and V construction. Cables shall beinstalled within walls, floors, or ceilings that provide a thermal barrier of material that has atleast a 15-minute finish rating as identified in listings of fire-rated assemblies.

Exception to (2) and (3): For buildings or structures required to be of Type I or Type II construction, Type NM, Type NMC, and Type NMS cables shall be permitted to be used,provided that where so applied in buildings or structures exceeding three stories above grade, circuits run in Type NM, NMC, or NMS cable shall not leave the floor or dwelling unit from which the circuits originate
 
I'm not clear why there's so much focus on romex vs. fire rating ?

It made sense to me to forgo receptacle outlet boxes in the same 'stud bay' , or fire caulking vertical installs

but what does romex assume for the spread of fire that makes it any different than say, LTNM? PVC?



~RJ~
 
romex jockey said:
I'm not clear why there's so much focus on romex vs. fire rating ?

It made sense to me to forgo receptacle outlet boxes in the same 'stud bay' , or fire caulking vertical installs

but what does romex assume for the spread of fire that makes it any different than say, LTNM? PVC?



~RJ~
Click to expand...

I have heard it questioned around 30 years ago - why is it safe to use NM cable in our homes where we sleep at night, but unsafe to use in some public places, where people are generally not sleeping. Place of assembly? Ok maybe some fall asleep like during the sermon, but there are many people there to wake them up should the NM cable start the place on fire.
 
Status
Not open for further replies.
Top