Wiring to Fluorescent Light Fixtures


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Old 01-28-04, 03:21 PM
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Wiring to Fluorescent Light Fixtures

I am installing some two-bulb, surface mount fluorescent fixtures in my basement remodel. The instructions that came with them say to use conductors with a rating of 90 degrees C. The 14-2 NM-B cable I have has no temperature rating printed on in anywhere, but I suspect it is not suitable. So what do I use? The folks at Lowe's, and my Basic Wiring book, are no help. Does this mean I can't use plastic ceiling boxes as well?
 
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Old 01-28-04, 04:09 PM
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If you can find some exposed cable (garage, unfinished basement, crawl space, attic, etc.), you can usually find it marked "NM-B" for 90-degree wire, or "NM" for 60-degree wire.

If you search this electrical forum for "degree wire", you will find many other posts that talk about the 90-degree wiring requirements. There are three basic ways of dealing with 60-degree wire:
  • Return the fixture and buy one without the warning. Pendant fixtures usually do not have this warning.
  • Replace the wiring from this box to whatever other box it came from with new wire.
  • Add a new, permanently accessible junction box a few feet away from the existing box, and use new wire between the boxes. Use a blank cover plate on the box that you are not using for the fixture.
The idea is to keep old wire away from the heat of the new fixture.
 
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Old 01-28-04, 04:41 PM
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Thank you, but I guess I didn't adequately explain the situation. I am not replacing existing fixtures with fluorescent ones. I am building a room in a previously unfinished section of my basement. This room will have its own circuits with all new wiring and lights.

The wire I am using is marked NM-B, which I deduce from your answer is rated for 90 degrees C. Is that correct?
 
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Old 01-28-04, 04:44 PM
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Yes, NM-B is 90 degree wiring.
 
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Old 01-28-04, 04:54 PM
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Great, thanks. Now, can I use plastic boxes?
 
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Old 01-28-04, 04:58 PM
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How do the flourescent lights hook up?
 
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Old 01-28-04, 05:05 PM
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The fixtures have a small knockout in the center, and are designed to attach to the ceiling using two toggle bolts or screws into the joist if they happen to line up that way. The instructions say to pull the supply wires through the knockout and make the connections inside the fixture.
 
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Old 01-28-04, 05:06 PM
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Then you don't need a box.
 
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Old 01-28-04, 05:08 PM
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Great, thanks.
 
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Old 01-28-04, 05:36 PM
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You do, however, need clamps for the knockouts.
 
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Old 01-28-04, 06:08 PM
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Even though you don't need a box, I recommend one anyway. They are very dirt cheap, they will provide a nice outline to cut the drywall around (if you use drywall), and you may replace the fixture in the future with a different kind that does need a box. You may even remove the fixture someday and not replace it and the box will provide a place to house the wiring.

Pick out the fixture before you drywall. That way you'll know where the mounting holes are and you can install 2x4 blocking to securely mount your fixture.
 
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Old 01-28-04, 06:35 PM
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Thanks. I've already done that.
 
 

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