combustible material

[rhy_fraser]

I have a question and am looking for some advice. This is in reference to 2011 NEC 314.20,,,, as stated, the front edge of a box can be within 1/4" from the finished surface unless the surface is considered combustible. My question, is acoustic ceiling tile in grid considered combustible? I am unable to find a fire rating on the package. A lot of times when mounting to a box in the ceiling if there is 1/4" space between the box and the surface, the fixture or bracket tends to "suck up" to the tile better to reduce a chance of gaps. If the box is flush and the fixture is somewhat heavier or awkward, like an exit light with battery packs, then it tends to pull the box down and create a gap. Any advice on this would be much appreciated. Thanks! Rhyan

 

[kwired]

I say it depends on the tile used. If it is a fire rated tile it should qualify as non combustible (or at least low enough combustibility). Most cheaper grade tiles I believe are not considered non-combustible.

 

[Sierrasparky]

I say it depends on the tile used. If it is a fire rated tile it should qualify as non combustible (or at least low enough combustibility). Most cheaper grade tiles I believe are not considered non-combustible.

I would agree that it depends on the tile.