So my 7 year old son I are working in our finished basement room last night. He's helping me install some wire for a switch above my drop ceiling in my office. We've got a few tiles moved and the wire stapled up. I went to the garage to get my fishtape and I hear the sounds of a crash.
The main in the grid wires came off the hook and brought 12-15 tiles and bars down with it including one lay-in light sitting on the floor, romex still connected. Yes, Yes, I know the light is supposed to be independently supported and the grid wires through holes not hooks.
I called the builder and electrician to complain and get it repaired. It doesn't work so well when I am both. This will be a fine example of doing it right the second time.
(B) Suspended Ceilings. Framing members of suspended ceiling systems 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 luminaire(s) shall also be permitted.
Local building code may require independent support of lay-in fixtures, or job specs, but not the NEC.
I was changing out the lights in a lodge a few years ago in a drop ceiling. I popped out the first light in the grid and the surrounding ceiling buckled. It turned out the ceiling was supported by speaker wire and some of it failed. The only thing that kept it from falling was the light and tension.
Years ago when I was working with my old boss we were working on a "Hot" job where they were trying to get in by the end of the month. The GC had a bunch of his flunkies working putting up ceiling grid and my boss and I were wiring up lay in fixtures. The carpenters were using ( it looked like #16 ga) thin tie wires to hook up the grid and they were suppose to go back and attach the lights. Well the GC is barking at all of us to keep moving cause we were falling behind and we had to get the job done. Next thing you know there was a loud crash and around 200 sq ft of ceiling tile and grid falls to the ground. My boss had his 12 year old son with us that day helping us. I was on top of a 6' step ladder when a light falls down heading for my son's boss. I caught the stupid light from hitting the son, but I suffered several cuts to the hand. The sheet metal was often very sharp. We all started to yell at the GC to shut up and slow down before some gets killed.
That worked for about 15 min. So we went home and started over the next day. We let the carpenters get the grid up with the right wire and enough wire to safely support the ceilings and lights.