# Suspended ceiling support



## erics37 (May 7, 2009)

Light Fixture Hanger Wire Requirements


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## OaklandElec (Jan 4, 2011)

erics37 said:


> Light Fixture Hanger Wire Requirements


Thanks...that tells when seismic wire is needed, but not about screwing the fixture corners. Help anyone?


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## cultch (Aug 2, 2011)

It's prolly local. We used to be able to tie 2 corners. Now we have to tie all 4. I don't screw to the grid tho. The wire will keep it from falling and it's easier to lift it out of your way if need be. They say the grid goes up in flames quickly in a fire so it's not much use for support.


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## erics37 (May 7, 2009)

OaklandElec said:


> Thanks...that tells when seismic wire is needed, but not about screwing the fixture corners. Help anyone?


Sorry, didn't read your post all the way.

The instructions usually just say basically "Set the light in the grid, attach required seismic wires, and ensure that light fixture earthquake clips are set properly."

I don't think screwing the corners is necessary or required unless a local code or the instructions dictate.


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## Bulldog1 (Oct 21, 2011)

We usually screw each corner to the main T.


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## OaklandElec (Jan 4, 2011)

Bulldog1 said:


> We usually screw each corner to the main T.


Us too, but some old timers claim you only need to do opposite corners. I was taught to do all 4 when I first moved to CA, but have never actually seen where it says you have to. I have seen inspectors call it though...


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## Gaterhater (Nov 15, 2011)

This is one of those subjects that changes from county to county, city to city, or state to state. It's seems to be getting closer to a standard though. Usually two separate means of support are called for( opposite corned grid wire being one). Hurricane clips, screws, or those cheap tabs you can bend out usually suffice for the second.


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## sparkie2010 (Sep 15, 2009)

OaklandElec said:


> Trying to figure out where and what the code is as far as far as supporting 2x4 fixtures in a T-bar ceiling. I've always done 2 seismic wire at opposite corners, and screw all 4 corners to the main runners. NEC 410 doesn't get that specific. Is it in the CBC? Local authority?
> 
> Thanks.


Two or four supports depending on AHJ


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## cabletie (Feb 12, 2011)

In my opinion there never was or never will be a definitive answer on this subject, no matter what any code book says. Ask the ahj what he wants. If you can push the fixture up it is probably no good. If the fixture can fall out of the ceiling if there was no ceiling it is probably no good. I believe there is also building codes on the subject as well.

I know a lot of people screw 2 corners. I prefer 2 screws in the middle. It seams to hold the fixture better when closing the cover or re-lamping. We have been using the caddy speed links that are shaped like a Y for years now and I have not heard any complaints from inspectors or bosses.


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## randomkiller (Sep 28, 2007)

The building code is where you should find those details and some localities have further requirements.


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## manchestersparky (Mar 25, 2007)

OaklandElec said:


> Trying to figure out where and what the code is as far as far as supporting 2x4 fixtures in a T-bar ceiling. I've always done 2 seismic wire at opposite corners, and screw all 4 corners to the main runners. NEC 410 doesn't get that specific. Is it in the CBC? Local authority?
> Thanks.


NEC article 410.36(B)
Suspended ceilings. Framing members of suspended ceiling sytems used to support luminaires shall be securely fastened to each other and shall be securely attached to the building structure at appropriate intervals. Luminaires shall be securely fastened to the ceiling framing member by mechanical means such as bolts,screws,or rivets. Listed clips identified for use with the type of ceiling framing member(s) and luminiare(s) shall also be permitted.

This says that the ceiling must be attached to the structure and the framing members secured to each other. This also says you shall screw,bolt, or rivet the light to the framing member of the ceiling. (I would go as far as saying the main runners not the Tees) You can use clips that are listed for the type of ceiling(layin) and the type of fixture your using ( Lay in). Caddy makes one that clips over the top of the grid and holds the lay in in place.
I would also verify the requirements of the jurisdiction your working in. They often have an admendment that they enforce. In my jurisdiction we require that all 2x4 lay ins have a minimum of 2 ties to the structure on opposite corners. Recess cans are required to have a minimum of 1 tie to the structure. Any boxes in ceiling for receptacles are required to have a minimum of 1 tie to the structure as well.
Yes we have this as an admendment to the adopted code.


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