Wiring Cieling Lights

[nwav8tor]

I'm planning on surface mounting numerous twin bulb 4' T8 fixtures in my attached garage. They'll be mounted directly to the ceiling sheetrock and I hope to be able to simply pull the "romex" into each fixture through holes drilled in the sheetrock.

1) Is that acceptable to do without using junction boxes in the attic?

2) If boxes are not required, do I have to use cable clamps at each fixture or can I just staple the wire at the nearest joist (24" o.c.) and use grommets to prevent chaffing where the wire enters the fixture?

Thanks,
Paul

 

[hevnbnd]

Boxes are required by code, however I have seen tons of these fixtures wired just like this...

 

[MrMark]

The light fixture has the "box" in it. It is the wiring compartment. You need a cable clamp to secure the cable to the KO in the light.

 

[matt151617]

Are the lights rated for flush mount? If not, you risk overheating them. They need the extra air space above to cool.

 

[nwav8tor]

Thanks for the replies...

The fixtures will be properly rated for surface mounting, not just hanging shop lights...

When using clamps in the K O, I was concerned that the clamp threads and nut might extend up too high for the fixture to lay flat and level on the ceiling. I hope the "dimples" on the back of the fixture to space it away from the ceiling are deep enough to allow this. I want the wiring hole in the sheetrock to be as small as possible so as to be easily sealed to prevent moisture/vapor intrusion into the attic...

Paul

 

[MrMark]

You need a big enough hole to clear the clamp.

 

[Familyof8kids]

Some of the BigBox store fixtures are not rated for internal joints. If the fixture has long wires then it is labeled as exterior joints normally. If the wires are short then it is approved for internal joints normally. Local codes can override all if job is being inspected. You have to support the wires 12" from the fixture with an approved nail or similar if the wires enter a box or the fixure. Cannot have more than 2 wires in and out on almost all fluorescent fixtures. No 3 wire joints allowed in the fixture. If you turn the bolt part of the romex connector inside the fixture then you can double nut the romex connector so it does not cause the fixture to sit non flush. Hope that made sense on how to use an approved romex connector. You also have to have both wires in the same romex connector. That is why you only see one hole in the fixture on each end and sometimes in the middle.

I manage some of the largest commercial/industrial lighting projects in the US and our sister company MFG's 90% of our own fixtures in Nashville, TN.

 

[nwav8tor]

Some of the BigBox store fixtures are not rated for internal joints. If the fixture has long wires then it is labeled as exterior joints normally. If the wires are short then it is approved for internal joints normally. Local codes can override all if job is being inspected. You have to support the wires 12" from the fixture with an approved nail or similar if the wires enter a box or the fixure. Cannot have more than 2 wires in and out on almost all fluorescent fixtures. No 3 wire joints allowed in the fixture.

I guess that means you must have a junction box in the ceiling above the first fixture on the circuit if you want to run a second string of fixtures controlled by a different switch on the same circuit. I was hoping to make a 3-wire connection inside the fixture to power the other string. Where does it indicate that the fixture is only rated for 2 wire connections?

If you turn the bolt part of the romex connector inside the fixture then you can double nut the romex connector so it does not cause the fixture to sit non flush. Hope that made sense on how to use an approved romex connector. You also have to have both wires in the same romex connector. That is why you only see one hole in the fixture on each end and sometimes in the middle.

I believe that you're saying to put the clamp end of the romex connector inside the fixture with one nut on the inside then when the outer nut is tightened, it won't protrude enough to cause the fixture not to sit flush. Is that correct?

Thanks,
Paul

 

[Familyof8kids]

Yes for the Romex connector you are spot on.

Not all fixtures are labeled the same. UL allows different labeling for different MFG's and I am not for sure on the differences. I know in our MFG line we have more data on different fixtures and head of MFG told me that is a UL requirement for that certain fixture.

Can you provide the model number, MFG, etc of the fixture you have or want to purchase?

 

[nwav8tor]

I haven't purchased the fixtures yet, but I'm looking at purchasing from HD or Lowes. I've looked at the boxes and don't recall seeing anything about the number of wires allowed to be connected inside the fixture. Next time I'm there, I'll look inside for more info...

Paul

 

[Familyof8kids]

It will all come down to allowed wires by the MFG of the romex connector and the size of the wiring entry in the light fixture. MFG manager just told me that fixtures follow the allowed wires per knockout. If your fixture has a 3/4 knockout then you can terminate 3 wires in the fixture but said if you enlarge the hole from 1/2 to 3/4 you are on your own and have voided the UL rating.

1/2" knockout but 7/8" hole is max of 2-12/2 romex
3/4" knockout but hole is 1 1/8" hole is not normal in a shop light but said 3-12/2 romex max

Above data is only valid if romex connector MFG has labeled the package to display allowed wires. All bigbox store romex connector say max wires allowed.

 

[nwav8tor]

Thanks FO8K, I'll keep all that in mind when I buy the lights and plan the wire runs...

Paul