2x4 in suspended ceiling

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iwire said:
Perhaps so they will not fall down and kill people?
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I thought that's why they got attached to the deck ABOVE.
Don't firemen rip the ceilings down?
 
celtic said:
I thought that's why they got attached to the deck ABOVE.
Don't firemen rip the ceilings down?
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Then for this to be the case we would have to completely ignore 410.16(C).

Roger
 
Around here (S. Fla) we have one of two choices: we can either screw them to the grid (mains, not cross tees) or we can tie them to the deck above. As iwire noted they could fall and kill people. Celtic is on the right track though, we had an incident here locally a few years back where a fireman was killed by a fixture that had not been tied off. When there is a fire, they break up and tear down all the ceiling tiles to prevent smoldering and spread of fire, smoke, etc. The fireman was doing such a thing when one of the fixtures broke loose from the grid and killed him.
Circumstancilally, we even have to tie off any exit lights, high hats (cans), or other such fixtures so that nothing is supported solely by the grid or tile.
 
roger said:
Then for this to be the case we would have to completely ignore 410.16(C).

Roger
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I haven't worked on lay-in type fixtures in quite a few years, but previously, every fixture had to supported to the deck above on opposing corners of the fixture...the same held true for ALL fixtures in a tile cieling (like bstoin said).
I don't know if that requirement was siesmec or fire code related....I can't say with 100% certainty that BOTH attachment means were/were not required - it's been awhile.
 
2x4 in ceilings

2x4 in ceilings

In fact in some seismic zones they must be supported independantly of the ceiling grids, so they don't fall down and kill people in an earthquake.
 
Never really understood the requirements. On one hand your have to clip the fixture to the grid so that the two are tied together. Then you have to independantly support from the structure above so that the two will not be tied together.

I think the reasoning is something like if there is an earthquake the runners and cross ties can spread apart. If this happens, you don't want the fixture to fall through the grid so you clip it all together. However, if the eathquake is serious enough that the whole ceiling grid comes down, the wires from the corners will prevent the fixture from coming down with it.

The IBC requirements are different depending on the weigh of the fixture. I don't have a book in front of me but I know if the fixture weighths less than 56 lbs you need 2 wires (slack) and the clips. More than 56 lbs and it has to be independantly supported from the ceiling. (Tight wires)
 
In my area all we have to do is drop it in and bend the 4 tabs on the fixture over the grid. I just did 120 last week.
 
sceepe said:
Never really understood the requirements. On one hand your have to clip the fixture to the grid so that the two are tied together. Then you have to independantly support from the structure above so that the two will not be tied together.

I think the reasoning is something like if there is an earthquake the runners and cross ties can spread apart. If this happens, you don't want the fixture to fall through the grid so you clip it all together. However, if the eathquake is serious enough that the whole ceiling grid comes down, the wires from the corners will prevent the fixture from coming down with it.
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sceepe,

Another reason that you need to attach the fixture to the grid and also independently support the fixture, is that in the event of an earthquake, if the fixture is not attached to the grid system it will swing wildly and tear the grid system apart.

Chris
 
well i thought u have to use those hurricane clips on the 2x2 or 2x4's and jack chain from the decking to support anything that weighs 35lbs or more that are dropped into drop ceiling grids
 
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