Supporting conduit

I've read that flexible conduit needs to be supported every 4 1/ 2 feet and within 12 inches on each side of every outlet box or fitting. If I have a span greater that that distance what is the best method of providing horizontal support?

Specifically I have florescent light fixtures hanging from steel beam roof supports with flex conduit running between them. The distance between lights is around 8'. At one point there was a drop ceiling and I'm guessing the flex was just sitting on top the ceiling tiles, but all that has been removed and the conduit between lights is just hanging in air.

 

The flex cable should have been supported by being attached to separate steel wires that were attached to the overhead steel and the ceiling grid - but did not support the ceiling grip - when that was in place.

The wiring for an open ceiling should be run on the building structure and follow a support wire down to each fixture.

If the fixtures that are hanging now are 2X4 lay-in fixtures, they are probably not rated for use as hanging fixture.

 

I'll check the fixtures to see if they are rated for hanging.

The conduit might be a problem as the roof is support by steel beams with insulation under them. There doesn't appear to be any easy method of dropping wires every 3.5' to support the conduit.

Could threaded rod be dropped vertically, say every 10-12' and then some sort of horizontal run be put in place to support the flex?

 

When you stand in this space and look up you can only see insulation? None of the roof support system is visible?

Some pictures might help us see what you have. See How To Put Pictures In Your Post.

Not that it makes a lot of difference, but Is it conduit with individual conductors pulled through it or is it metal-sheathed cable? More to the point, what are the fixtures suspended from?

No one has suggested that you drop wires to support the cables or conduit. What I suggested was that That is, the wiring should be run overhead and be attached to one of the existing fixture support wires between the building structure and each fixture.

Yes. You would need to use 1-1/2" uni-strut or a similar product, mounted with the open face toward the floor. It will need to be made continuous with splice plates and supported at intervals no greater than 10'. Both the fixtures and the wiring will need to be attached to the support strut assembly.

The best work platform for this work is a scissors lift. It will be a lot easier with a helper. I would start by setting up a couple of work lights on stands and demoing all of the existing lighting. Unless it is is modern lighting with electronic ballasts and T-8 lamps, this would be the ideal time to upgrade it.

What will the all-thread be mounted to?

 

As Nashkat posted, upload a picture of what your working with and we could suggest fittings that you can use. There are a great deal of fittings and products that are used to connect all sorts of hangers to beams and the like. I am sure we could come up with something.

I would also suggest using MC cable or similar for wiring lights.

 

Thanks guys, I'll be able to get some pictures this weekend and look to get a better idea of the existing.

 

This sounds like it might be a commercial space. If so the OP may need a licensed contractor to do the work.