Is it a good wiring practice in a commercial building to come thru a hole in the dry-wall ceiling with romex wire and drop 8" to a lay-in fluorescent fixture or recessed fixture in a suspended ceiling? Should there be a box at the hole in the dry-wall ceiling? Can the romex be unspported? Can the romex run into the fluorescent fixture with out a box? Thanks for any advice, I use a box with a whip. Boomer
I think if the occupancy rate is under 100 people you are permitted to use romex as a wiring method. Using it in the suspended ceiling could be a different story. Many times the area above the suspended ceiling is considered a plenum. Romex is not permitted for use in a plenum.
Re: Suspended Ceiling#83058 01/07/0307:27 AM01/07/0307:27 AM
If the drop ceiling is "plenum", NMC is not allowed. If you are penetrating sheetrock in a fire rated ceiling you cannot "punch thru"; the "hole" must be sealed to maintain fire rating.
Wiring (two cables) into a troffer fixture is acceptable. Boxes and whips are acceptable.
Any cabling within a drop ceiling has to be supported independently of the drop ceiling grid. There is a max. length that can be unsupported between fixtures, I believe it is 5', but I'm not positive. (Please read the articles in the NEC)
Also, all low voltage wiring in a plenum ceiling must be "plenum rated", and recently, another AHJ found an article requiring "Plenum Rated" tie wraps.
Iwire: Not to be a pain in the butt...is the tie wire that you use listed for use as a support for MC cable???
THe plenum tie wraps are mostly used for LV cables (yes, plenum rated LV cable). The MC is usually supported with Caddy clips to seperate drop wires that are "secured" to the ceiling grid with more Caddy clips. All of the above items are listed for the usage. I don't have the Caddy book on hand right now. John
HotLine1, not a pain in the butt. Damn good question I would have to say no.
That said, I had inspector in Mass. tell me that plastic tie wraps are not listed for support of MC and that soon I may not be able to use them at all, (I do not know the truth of this) his reasoning seemed to be they melt early in a fire and drop stuff down onto firefighters.
This being Mass, where we must tie lights independently from ceiling I can certainly believe this.
I have never been shot down for it.
As far as the caddy clips we use those too but the tie wire is faster, cheaper most times, you carry a roll of tie wire instead of a variety of caddy products.
We try hard to follow the building structure so we do not have horizontal runs down near the grid when we do its Caddy clips
Down the metal studs we end up using Caddy
[This message has been edited by iwire (edited 01-09-2003).]
Bob Badger Construction & Maintenance Electrician Massachusetts