proper support of luminaires in hung (suspended) ceiling?

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ritelec

Senior Member
Location
Jersey
Good morning all.

I will be installing some downlights in a hung ceiling.
In reading around 314.23 (D) , It looks like fastening to the grid is enough (1).

Yet (2) mentions support wires....
In the past I've installed the lay ins (flourescents) that at the time just had to be secured to the grid.
Then several years ago the fixture also required it's own support wire (wires) also.

Where is it stated that these 2x2 or 2x4 flourescents "have to be supported with support wire also?

Is there a weight or size issue that I'm not finding?
Does it have something to do with the 100 inches cubed inches in (D) ?

Are high-hats required to be both secured to the grid and have separate support wires to the building???


Thank you,
Rich
 

kwired

Electron manager
Location
NE Nebraska
I can not ever recall NEC requiring support wires being attached directly to the luminaire. It has always pretty much stated the luminaire must be fastened to the grid and the grid must be supported in a way to handle the load.

I think in cases where they are requiring support wires to be attached directly to the luminaire or even to the grid at each corner of the luminaire is either a local code or maybe interpretation of what it says by inspector or the AHJ he works for.

You could possibly have codes other than the NEC that are making this requirement also.
 

iwire

Moderator
Staff member
Location
Massachusetts
Read the title of Art 300.

Now go to Art 410 for requirements for luminaires, specifically 410.36(B).



Well, I won't argue this one, I could be wrong.

But I do know for fact that luminaries have to be independently supported from the grid in MA, CT and RI. Could be building codes.

MA goes so far as to amend away the NEC requirement to secure them to the grid.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
Here is my take: 410.36(B) only applies if independent support for the fixture is not provided.

So, if you provide independent support for the fixture, you are finished. No need to read on, except you have to tag the independent support wires.

If you don't provide independent support, then you must:

1. Provide adequate support for the ceiling framing.
2. Secure the fixture to the ceiling framing.
3. Secure the ceiling framing members together.
4. Refer back to 300.11 (A) 1 and 2;
... 1. If the ceiling is a fire rated assembly, the fixture has to have been tested as part of that fire rated assembly. Otherwise, back to the independent support.
... 2. If the ceiling is not a fire rated assembley, the fixture has to be installed per the ceiling systems instructions. Otherwise, back to the independent support again.
 

kwired

Electron manager
Location
NE Nebraska
Here is my take: 410.36(B) only applies if independent support for the fixture is not provided.

So, if you provide independent support for the fixture, you are finished. No need to read on, except you have to tag the independent support wires.

If you don't provide independent support, then you must:

1. Provide adequate support for the ceiling framing.
2. Secure the fixture to the ceiling framing.
3. Secure the ceiling framing members together.
4. Refer back to 300.11 (A) 1 and 2;
... 1. If the ceiling is a fire rated assembly, the fixture has to have been tested as part of that fire rated assembly. Otherwise, back to the independent support.
... 2. If the ceiling is not a fire rated assembley, the fixture has to be installed per the ceiling systems instructions. Otherwise, back to the independent support again.

Comment on your #4 - back to what I mentioned earlier, art 300 is "wiring methods" the requirements for "luminaires" is in art 410. None or very little of the language in 300.11 is in 410.36(B).
 

iwire

Moderator
Staff member
Location
Massachusetts
Comment on your #4 - back to what I mentioned earlier, art 300 is "wiring methods" the requirements for "luminaires" is in art 410. None or very little of the language in 300.11 is in 410.36(B).

Consider this, is the junction enclosure at the luminaire not part of the branch circuit wiring?


300.15(J)
 

cowboyjwc

Moderator
Staff member
Location
Simi Valley, CA
I've posted the answer before, but again you can't always rely on the NEC, this is in the T-Bar standards.

"Light fixtures weighing less than 10 pounds shall have one, No. 12 gage hanger wire connected from the fixture housing to the structure above."
 

kwired

Electron manager
Location
NE Nebraska
Consider this, is the junction enclosure at the luminaire not part of the branch circuit wiring?


300.15(J)
Luminaires are permitted to be used as raceways, but for limited applications as mentioned in (410.64)the section 300.15(J) refers us to.

I don't consider a luminaire to be a "general wiring method", like raceways, cables, or associated "utility boxes"
 

iwire

Moderator
Staff member
Location
Massachusetts
Luminaires are permitted to be used as raceways, but for limited applications as mentioned in (410.64)the section 300.15(J) refers us to.

I don't consider a luminaire to be a "general wiring method", like raceways, cables, or associated "utility boxes"

Sorry,wrong section.

300.11(A)
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
Comment on your #4 - back to what I mentioned earlier, art 300 is "wiring methods" the requirements for "luminaires" is in art 410. None or very little of the language in 300.11 is in 410.36(B).

And back to Bob's comment about equiment and the definition of equipment. Also, the handbook commentary specifically states that luinaries aren't allowed in a fire rated ceiling unless they are part of the listed fire rated assembly.

The same reasoning and logic means that 300.11(A)2 also applies to luminaries.
 

cowboyjwc

Moderator
Staff member
Location
Simi Valley, CA
Does that include the (often substantial in the case of LED replacement bulbs) weight of the bulb, or just the empty fixture? :)
Well the section comes out of the T-Bar standards so I'm sure that the term "luminaire" hasn't caught up to them yet. Here in earthquake country we get a wire on every box in the ceiling.
 

kwired

Electron manager
Location
NE Nebraska
Well the section comes out of the T-Bar standards so I'm sure that the term "luminaire" hasn't caught up to them yet. Here in earthquake country we get a wire on every box in the ceiling.
I can understand things being a little different where seismic activity is common, as well as a difference between fire rated and non fire rated. But for a non fire rated outside the seismic areas, if the grid is properly supported and the luminaire is secured to the grid as required, where is it going?

I can't say I have ever seen a true fire rated suspended ceiling, but would guess that a luminaire rated for one would probably be much heavier than a non fire rated luminaire, so I could see it needing additional support just because of its weight. Most ceilings I have ever seen where a fire rating is likely required have drywall on the structural ceiling above but same grid system that is used anywhere else - and probably not fire rated.
 

cowboyjwc

Moderator
Staff member
Location
Simi Valley, CA
I can understand things being a little different where seismic activity is common, as well as a difference between fire rated and non fire rated. But for a non fire rated outside the seismic areas, if the grid is properly supported and the luminaire is secured to the grid as required, where is it going?

I can't say I have ever seen a true fire rated suspended ceiling, but would guess that a luminaire rated for one would probably be much heavier than a non fire rated luminaire, so I could see it needing additional support just because of its weight. Most ceilings I have ever seen where a fire rating is likely required have drywall on the structural ceiling above but same grid system that is used anywhere else - and probably not fire rated.
A lot of it has to do with the fire department, when they go in and start tearing down the ceilings they don't want the fixtures coming down too.
 
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