Does the code say you can strap conduit to ceiling tile hangars with the approved straps. I'm pretty sure I've seen it in commercial buildings and probably done in my younger days:) Just want to make sure. Going to have to run some conduit in old ceilings for a pretty long distance with nothing else to really support it. Original ceiling is way higher than the "dropped portion". Thanks
You have to use your own #12 drop wires -- in my area these are spray painted green or red to mark them as EC provided.
Then you can use
kx (MC) k-8 (1/2) k-12 (3/4) k-16 (1)
sometimes referred to as 'batwings.'
1/4 smooth drop rods are available from Hilti and others.
These can be shot into overhead concrete and steel.
They don't require tying off to the grid. They make the most sense in new TIs. One can run EMT above the lid and not revisit the work to tie it off -- something required if you use #12 ceiling drop wire.
Tesla, do you know the code reference to that. I do remember something about the separate coloring for the tie wire it seems. I think I did a job a while back and I was required to install or paint the tie wires a different color that held the light fixtures up. The location was in a private school setting. Thanks again..
From the 2011 NEC "300.11 Securing and Supporting. (A) Secured in Place. Raceways, cable assemblies, boxes, cabinets, and fittings shall be securely fastened in place. Support wires that do not provide secure support shall not be permitted as the sole support. Support wires and associated fittings that provide secure support and that are installed in addition to the ceiling grid support wires shall be permitted as the sole support. Where independent support wires are used, they shall be secured at both ends. Cables and raceways shall not be supported by ceiling grids.
Note that the 'extra' wire that is installed for electrical use, shall be supported at 'both ends'! That means that it has to be connected to the grid,
Caddy makes (made) a yellow item that clipped onto the grid to 'secure' the electric support wire.
As to the color of the wire, I do not know of a 'code' reference; I believe it is a local thing. Guys here use red, green, yellow paint.
The 'yellow' clips were touted as a means for an AHJ to determine IF the wire used for electrical support is for that purpose only.
FWIW, I have not seen anyone install conduit above a drop ceiling supported by wire. Not saying it is not done, but I have not encountered it.
The move to independent drop rods started in the last decade.
The NEC was changed after the 1994 Northridge earthquake.
Survivors told of light fixtures hitting them in the head -- all over town -- after the grid went down. These events also opened up the flex/ MC and set the stage for electrical fires.
ERICO's stuff -- way back when -- was touted as supporting LV data-com over the grid. (Bridle rings) IIRC these are still available.
The earthquake revealed that -- particularly in grocery stores (the cheapos) -- that ultimately massive groupings were built up over the grid. So much so that they contributed to the grid's failure.
So the California building code shifted towards independent support for data com cabling, too.
The reasoning being that the grid ought to hold up much better -- and not hit so many on the head. (Victims just could NOT avoid the impluse to look UP into the falling debris. Eye and facial injuries were the result.)
Spray painting drop wires proved to be vastly cheaper than the Caddy product fix. For the purposes of the building code, it's not necessary for these drop wires to run taut and straight. Close enough will do. The last thing you want to do is induce pucker -- lifting and distorting the tile crew's excellent work.
Personally I became a fan of independent support tha day that I saw the entire drop ceiling in one of out plant areas fail (support wires had corroded) and the light fixtures were still hanging in mid-air on their separate support wires instead of smacking someone on the head.
1/4 smooth drop rods are available from Hilti and others
They don't require tying off to the grid.
I worked on a Toyota Dealership in Northridge (2003), years after the quake.
The LA Inspector scrutinized everything involved with the independent support wires. Attached to grid, 5 full turns of the wire within 1-1/2". He even went as far as taking a 12" ruler to see if the conduits, data/comm lines, etc. were up high enough that they didn't interfere with the removal of the tiles.
Most drop-in fixtures come with flimsy little fold out tabs to attach the drop support wires. 5 full turns on the drop wire is extreme overkill. The fold out clips that attach the fixture to the grid are cheesy too but the inspectors are accepting them instead of screws.
The trick is to doing it is to hold the tab for the wires with a pair of needlenose as close as you can to the hole. Insert the wire through hole, bend it over and put a 90° in the bend in the so it forms a crank to wrap the tag end around the wire.
I agree it's extreme overkill, but the tbar contractor was made to do the same, along with angled seismic splay wires, and solid compression struts up to the structure above every 12' or so on the main grid runners. The tbar guy used a ceiling wire inside 3/4" EMT for the compression struts.