drop-in fixtures

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ferrarotomvfjr

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can a 2x4 drop in fixture be wired with nm cable? I have been told no, but I thought the rule was the wire only need to be rated at 90 degrees if it is within 3 inches of the ballast.

[ October 19, 2005, 08:18 PM: Message edited by: ferrarotomvfjr ]
 
Re: drop-in fixtures

334-12-a-2 refures to wiring in a other than dwelling building, i live in mass and we have ammendments to that rule, my question was can i wire the light with romex even though it is not rated for 90 degrees, i could only find that i can as long as i keep the wires 3 inches from the ballast
 
Re: drop-in fixtures

I would say that type NM cable is rated for 90 degrees since it contains THHN conductors, but must be sized for ampacity at 60 degrees.
 
Re: drop-in fixtures

i thought that romex had thermoplastic wire not thhn? if so thermoplastic is rated for maximum 90 degrees, 410-33 says you cant use a lower than 90 degress wire for a luminare. so can i use it?
 
Re: drop-in fixtures

Well that a good question. It looks like THHN/THWN, probably is THHN/THWN but it isn't marked with anything. Around here an inspector will red tag you if you use the conductors from a piece of NM and run them in the sealtite going from the disconnect to an outdoor A/C unit. Has to be THWN (wet location) but it has no markings.

To answer your question type NMB is rated for 90 deg C. All our NM is NMB.

-Hal
 
Re: drop-in fixtures

If it is permitted in the ceiling, then the answer would be yes, it can be used for a troffer fixture.

334.80 says that NM cable is a 90 degree conductor.
 
Re: drop-in fixtures

First, thanks for all the great information. I have cruised this forum for a while picking up some really nice tidbits of very useful information.

Second, this is my first time posting so take it easy on me. I have read some threads and noticed some guys getting "jumped in" as if by a gang. If this post shows up in all caps, I didn't mean it I swear! :D

I wanted to add to the thread just a little as I have read several post about NM containing THHN/THWN conductors and the 90C rating of the cable. The UL standard (UL 719) for NM is pretty clear in paragraph 1.1 that both NM and NMC carry the "-B" marking. This indicates that today all NM cable be rated 90C as it is.

The standard also reads:
"6.1 Both before and after assembly into finished cable, the insulation employed on the circuit conductors shall comply with (a) or (b):
a)THHN Construction ? Jacketed insulation for a Type NM or NMC cable shall have a nylon or similar jacket and shall comply with the thickness and other applicable requirements for Type THHN thermoplastic-insulated wire without (see 25.18) any surface marking of ?THHN?, ?-B? or any ampacity or temperature rating.
b)TW Construction ? Insulation without a nylon jacket shall comply with the thickness requirements for a Type TW?

25.18 No conductor type letter designation and no current or temperature designation shall be included in the marking on the tag, reel, carton or directly on or in the cable."

As you can see all conductors in NM are THHN or TW. I think all companies actually supply THHN. Also you can see that it is not allowed in the standard to print the conductors with any marking such as "THHN/THWN". Therefore they are not allowed to be removed from the sheath and used as stand alone conductors for any location wet, dry, hot or cold.

This leaves the 90C rating for 2 reasons that I can think of. 1) Derating from the 90C column, but ampacities not to exceed 60C per 334.80. 2) Terminating in high temp fixtures.

Sorry for such a long post.
 
Re: drop-in fixtures

thank you- all i could find in the nec about this subject was, that first of all, the wires feeding a drop in light need to be rated for 90 degrees, second, if they are not than they need to be keept 3 inches away from the ballast, then i looked at the temp rating of romex , i found that it is rated for 90, but for ampacity it is rated for 60, so i would say that the forman of this job was wrong for making me go back and remove the romex from the lights and box them to run mc wasting company time and stock,, nyone agree?
 
Re: drop-in fixtures

Originally posted by ferrarotomvfjr:
so i would say that the forman of this job was wrong for making me go back and remove the romex from the lights and box them to run mc wasting company time and stock,, nyone agree?
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Maybe. It depeds on which edition of the NEC you are using. Starting with the 2002 edition, NM cable was resricted from use above suspended ceilings. 334.12(A)(1)

(A stupid restriction in my opinion, but that's another story. )
 
Re: drop-in fixtures

i am sorry, i did not tell you i guess, i am using the 2005 edition but i live in mass, we have an admendment to that rule
 
Re: drop-in fixtures

In that case, there was no reason to rip out the NM cable. But your NM cable still has to "closely follow the building finish."
 
Re: drop-in fixtures

well please read above, but i was asking if a romex wire can feed a drop in fixture, there was alot said above on this post so please reasd the top, i would apreatiate the input
 
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