How should I run wire for fluorescents?

[Toddyus]

I'm going to be installing 10 8' T8 fixtures (4, 4-foot bulbs) and I'm using the tandem fixtures from Lowe's (Cooper Lighting ~40 bucks/ea).

The lights have an extra large knockout in the center of each light, so my original plan was to run Romex along the bottom chord of the truss, mount the light on the chord, then drop the romex directly into the fixture through the large knockout. If the light is centered on the chord, there is probably, at it's widest point, 1/2"-3/4" of opening in the knockout for the romex.

The lights will be in three interconnected banks with one source wire coming into the first light in the bank. The next light would be pigtailed off of the first light, back out the knockout and so on.

The ceiling will be insulated and drywalled. I was not planning on using boxes.

Am I going to run into trouble with this approach? Anyone else do it this way? Anyone have direct experience with the Lowe's lights and how did you do it?

Thanks for any insights!

 

[mrb]

you cant punch out the large knockout and just drop romex into it. The large KO is for a box. Do the fixtures have normal 1/2" KOs?

 

[Toddyus]

you cant punch out the large knockout and just drop romex into it. The large KO is for a box. Do the fixtures have normal 1/2" KOs?

That's what I was afraid of. I'll take a closer look, but my initial inspection shows all the topside knockouts being down the center - right where the stud would be once I screw it down. There are a couple on the side, but I wanted to keep all the wiring in the ceiling.

Are the placement of the knockouts there by any particular required design, or could I just cut my own with a hole saw outside the stud area?

I feel like an idiot. This can't be this complicated...

 

[mrb]

not sure about cutting holes in the fixture for cable entry. I would think no because anywhere outside the center wouldnt be in the wiring area of the fixture.

Just mount a box matching the large KO to the bottom chord of the truss and put a couple spacers the same height as the box where appropriate to attach the fixture.

 

[Toddyus]

not sure about cutting holes in the fixture for cable entry. I would think no because anywhere outside the center wouldnt be in the wiring area of the fixture.

Just mount a box matching the large KO to the bottom chord of the truss and put a couple spacers the same height as the box where appropriate to attach the fixture.

That was my next thought...

 

[Falcon67]

FWIW - here is what I plan to do for my lighting. I plan on three 4' fixtures mounted in tandem with conduit. I'm going to place 2x4x6" (or some small length) "flanges" nailed 90 degrees to the joists to use for light mounts. They will be spaced so the lights can be screwed to those, leaving any 1/2" KO with clear access. A single 4" box will home the romex light run between the light rows, then MC cable will make the jump from the box to the fixture runs. The plan for the main work area is two rows per 3-way switch leg, 5 rows total. $100 cheaper to use 15 each 4' @ $20 than 10 each 8' @ $40. I'll also save $5 less in bulbs per row.

 

[TheEquineFencer]

If you screw the fixture to a truss, look at the rear side of the fixture, it should have four "dimples." These are to keep the fixture from coming into direct, flat contact with the wood or what ever you're mounting to. If it's hanging fixture with a chain, I'd put a cord/plug on it and mount a duplex receptacle. You can get a plastic insert at Lowe's that's made for Romex to run though the 1/2 inch KO holes, they are legal to use. Or you can use the Romex clamps that are made for metal boxes. There's no need for a 4 x 4 box unless in the future you want to expand the lighting system. Make all of your connections inside the lighting trough under the bulbs. I'd recommend getting the 6500 Kelvin rated T-8 bulbs, you'll like the brighter, cleaner daylight it gives off. My neighbor cheaped out and used the 4100 kelvin bulbs when they did their wash pit in their horse barn, then saw the same fixtures in our horse barn and could not figure out why ours was so much brighter with a "cleaner light."

 

[Aceman]

Don't overcomplicate this. I always try to run my lights perpendicular to ceiling joist/trusses just for this reason. It's easier to get into the fixture plus it's still easy to hit several trusses every 16/24 inches for anchoring it down.

But, if you want to run with the trusses, take your Romex and staple it loosely to the side of the truss near the top(farthest from the fixture) with the wire hanging down from the ceiling. Sheetrock around it, punch your own hole offcenter in the fixture if necessary and mount it up. You can punch holes anywhere you want in an 8' strip as long as you stay out of the dimples and ballast area.

For the record, I probably only use the factory ko's less than half the time. When you need lights dead centered in a room you are almost always shifting the fixture one way or another to do it, and that means making your own ko's to line up with the wire that's stubbed out.

Buy the gray plastic Romex connectors too, don't screw with those metal 2-screw clamp connectors. Those are a pain in the #$%.

 

[tfi racing]

Don't overcomplicate this. I always try to run my lights perpendicular to ceiling joist/trusses just for this reason. It's easier to get into the fixture plus it's still easy to hit several trusses every 16/24 inches for anchoring it down.

But, if you want to run with the trusses, take your Romex and staple it loosely to the side of the truss near the top(farthest from the fixture) with the wire hanging down from the ceiling. Sheetrock around it, punch your own hole offcenter in the fixture if necessary and mount it up. You can punch holes anywhere you want in an 8' strip as long as you stay out of the dimples and ballast area.

For the record, I probably only use the factory ko's less than half the time. When you need lights dead centered in a room you are almost always shifting the fixture one way or another to do it, and that means making your own ko's to line up with the wire that's stubbed out.

Buy the gray plastic Romex connectors too, don't screw with those metal 2-screw clamp connectors. Those are a pain in the #$%.

This is the way I have done it for hundreds of fixtures,the simplest method with the fewest possible connections/splices is usually the best way to go.

 

[dittle fart around]

Mount a 4X4 box at the start of the run of fixtures. Now you can offset the knockout of the box to clear the joists and use a sleeve and lock nut to connect end to the fixture. Makes the run legal and allows you to mount an outlet for pull down extension cord reel.

 

[Toddyus]

This is the way I have done it for hundreds of fixtures,the simplest method with the fewest possible connections/splices is usually the best way to go.

Good, I think this makes sense. I can fit two pieces of 14/2 in 1/2" KO of my own making with a romex clamp (have to check out the plastic ones; have only ever used the metal ones) for the in-feed and the out-feed to the next light and just staple each cable to the truss chord.

I do have a couple lights that will run perpendicular to the joists, but for how I want to use the space, I can't avoid some running in parallel.