Here's where architects earn their keep. A check of the appropriate UL directories will show numerous fire-rated suspended ceilings, where the ceiling grid supports the troffers. That means that, even after a fire test, the troffers remained in the grid- even if the grid was warped and twisted like a pretzel. Remember the words "according to the manufacturers' instructions." The UL tests do not take into account earthquake requirements- only fire.
Re: Fixture Supports in Suspended Ceilings#103763 11/26/0208:40 PM11/26/0208:40 PM
For what it's worth... We install drop wires for the troffers, usually get the ceiling contractor to install "extras" for the fixtures, and any cabling that requires support. The fixtures get a drop wire on each corner, and dependent on the local AHJ, some locations get "screwed/clipped" to the grid...some don't. The drop wire we use for cabling support gets a Caddy "yellow placement clip" to "secure" the drop wire to the grid. When ductwork gets in the way, we improvise as needed, EMT trapeeze, etc., etc. Hell we've been known to use a tin knockers support strap a few times. John