I'm using a "T" bar to support a 4" octagon box for an exit light in a lay in ceiling. I know Arlington makes a stud that a cable can be secured to that inserts into the back knock out of the box, but the screw and bracket for the t bar takes up the room. Any other ideas how to support the box independently of the grid and still use the "t" bar thanks

Use a 4" box with 5 KOs?

Greg, you talking about a 4" square with plaster-ring and off-setting the "t bar" support in the back and leaving the center hole open for the "Arlington" support? That might work. Looks like with the "T" bar support off set, it will make the fixture hang crooked since the weight will be off balanced. This exit light is an exit/emergency light and is sort of heavy. Thanks

000) It's usually quicker and cheaper to just throw in a box extending ring.

00) It's cheaper to just stay with basic 4s boxes -- deep -- and to use 3/0 rings -- 3/4" deep for all exit signs in a soft lid. (Occasionally 1" deep)

0) The spider ring -- always provided in an exit sign kit -- squeezes the tile between the 3/0 ring and itself -- which stops it from floating away during trim out.

1) It's much quicker to drill out the penetration with a hole-saw.

2) Space headaches are gone.

3) The geometry of support gets simple. Everything always lines up perfectly.

4) CADDY makes bar supports that mate perfectly with this scheme -- look at their product literature.

Spark there are 4" octagon boxes with 5 KOs in the back.

Something like a TP276 and you you can get a ring that gets you to 3" round.

This is cooper but I am sure the others have a similar product

http://www.cooperindustries.com/con...eel-octagon-boxes-covers-accessories.pdf

Thanks and yes I'm sure I've seen them. Just a "senior" moment there. Thanks a lot..