Is romex (NM) allowed to be used in the walls and ceilings of a horse barn in areas specified by 547.1 where it will be concealed by a finish surface such as wood on the walls and plastered ceilings?
shortcircuit
The way I read it, I think you're OK.
Can anyone explain what the last sentance of 334.10(3) means or maybe have a link to such list as described?
"Cables shall be concealed within walls, floors, or ceilings that provide a thermal barrier of material that has at least a 15-minute finish rating as identified in listings of fire-rated assemblies."
My concern is if romex (NM) is concealed behind finish walls of wood on the interior of a horse barn, is the wood wall finish acceptable as a 15-minute fire-rated assembly?
shortcircuit
As I recall, 1/2 inch wallboard has a 15 minute rating.
Let me check the UL book for others.
Nope, no wood. All the listed assemblies are gypsum wallboard, plaster, cement block, masonry or 24 gauge metal panels.
Now you got me going.
My rule of thumb is just not sufficient. the finish ratings go all over the chart, depending on the manufacturer and the product. Examples: American Gypsum Co. 5/8 inch Gypsum board Types AGX-1,2&3 have 23 minute finish ratings. AGX-5 has a 26 minute finish rating. US Gypsum Co. 1/2 inch Gypsum Wallboard (GWB) Types AR, FRX-G, SCX, SHX or WRX all have a 29 minute finish rating.
There are hundreds more. But, the lowest rating I could find for 1/2 inch GWB was 20 minutes. The rating for some 3/8 inch GWB was 8 minutes, so watch out!
The assembly also required paper tape over the joints, and usually a minimum of 2 coats of joint finishing compound.
Sounds like, to make your installation code compliant, you need to add 1/2 GWB over the walls of the barn where you have run the romex.
You can research them yourself at:
http://www.ul.com/fire/building.html Click on the picture of the front cover of the building materials directory.
Thanx earlydean, but I couldn't navigate through to where I could find specific listings on sheetrock and wood?
shortcircuit
So your saying that if a house is being built and they use wood paneling ,they would have to sheetrock it first?
What about those log homes , romex is channeled through them.
334.10(3) pertains to "other structures"
Not dwellings.
shortcircuit
Type NMC cable is specifically permitted in agricultural buildings.
547.5 Wiring Methods.
(A) Wiring Systems. Types UF, NMC, copper SE cables, jacketed Type MC cable, rigid nonmetallic conduit, liquidtight flexible nonmetallic conduit, or other cables or raceways suitable for the location, with approved termination fittings, shall be the wiring methods employed. Article 398 and Article 502 wiring methods shall be permitted for areas described in 547.1(A).
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Tom Horne
[This message has been edited by tdhorne (edited 06-09-2005).]
Tom- You'll not find NMC being manufactured to my knowledge by onyone. Next best thing if you are not faced with a subject to physical damage would be UF cable.
George, that was my impression the last time I went on a search for NMC. The wire manufacturers shunt you off to a UF product. They are pretty much saying NMC is UF from the manufactuer's standpoint.
Is there anything NMC can do that UF can't?