I have a light fixture that says to use a supply wire rated at 90° – I think the problem probably stems from the lamp holder being close to the wiring box on the housing, heat and the potential to bake the insulation. Am I ok in assuming that using Romex will be safe to use?
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It better be or they better re-wire every house in Arizona.
There's some job security! <grin>
If the cable was recently made, within the last 25 years or so, it is OK. You may be able to look at the jacket closely and find the designation something like: 'Type NM-B' or 'NMB'.
Most of of the more recent stuff will also have a translucent nylon coating over the colored plastic insulation on individual conductors.
So is it the heat issue? If so, won't bringing whatever supply line into a box away from the fixtures and run my own Romex from the box to the light do the trick? Thanks for the help!
Some jurisdictions will allow short lengths of 90C wire to be pigtailed onto the existing lower temperature wires so that a fixture requiring 90C wire to be used. A lot depends on how you do it. Usually I will cut the existing wires just a touch short, but still legal, and pigtail on the 90C wires using a good wirenut. The old wire and nuts are neatly tucked into the bottom of the box safely away from the heat of the fixture. I leave the 90C wires long and then cut 6" from the face of the box so that when they are coiled in they hold the old wire and nuts well away from the fixture. The fixture is made up and mounted in the normal manner. Note if a fixture comes with a piece of insulation, typically a wad of fiberglass cut to the size of the base it needs to be laid out neatly to cover the parts intended and, of course, not tossed away. Another thing that helps is to, where it doesn't create an eyesore, to use a sharpie to ink in the pressed in warning about using bulbs 60w and below. It also helps to warn the HOs about the hazards. For long term customers as they get on in years it is often helpful to suggest the fixtures be changed out, a few at a time, to ones which will take 75w or larger bulbs. Older eyes need more light. It is easy to see fixtures gradually over lamped. I once saw a 6 bulb unit intended for nothing larger than a 40w bulb loaded with 100w bulbs. It Really lit up the kitchen. It also smoked the wiring in the box it was mounted on and so dried out and damaged the drywall that when we took down the fixture a circle of drywall about 3' in diameter came with it. Even worse seemingly half the wiring in the house was routed through that box and the insulation and jackets on all the cables was burnt back so far we had to mount three or four boxes to get to good cable and get all the connection into boxes. Did I mention it was a tight attic and, of course, later on a summer day? When it rains ...
If more light is needed, an option is to switch to 75 or 100-watt "equivalent" CFLs. Of course, these won't fit all fixtures, but will probably fit most.
If ignorance is bliss why aren't more people
happy?
The trouble with CFL's in an overheating situation is that they'll cook themselves. You'll only get a fraction of the life from an expensive CFL than you would from a cheap incandescent. 40° C, let alone 90° C, will kill them, though they won't cook the wires up in the box like incandescents will.
I had one on a porch lite that was dead in a week and a half. Modifying the fixture to let air thru solved the problem, it works fine with CFL's now.
-- J.S.
The newer CFL ballasts don't throw out nearly as much heat as the old ones did.
If ignorance is bliss why aren't more people
happy?
Each ballast type, electronic or conventional wire wound, have advantages. The electronics are a little more efficient, run cooler and, some, have improved cold weather starting and more rapid climb to rated output. They also tend to be both lighter, important for table lamp use, and more compact, important if your trying to fit a CFL into a fixture not specially designed for it. Also electronic ballasts have less 'flicker'. Down side is, until recently, the electronic units were considerably more expensive and fairly vulnerable to voltage spikes.The conventional ballasts are cheaper and much more resistant to voltage spikes.
Design and quality vary a lot in CFL's. Most are made in China, so there are no established name brands.
-- J.S.
Pretty much all fixtures made since about 1980 have the 90-degree restriction. There are basically three reasons for this:
1) Often folks would load up a fixture with 100w lamps when the fixtures were only rated for 60w. This would lead to significant overheating of the fixture and damage to the wire.
2) Even with 60w lamps (or whatever the fixture rating was), the fixtures would often "bake" the insulation on older romex until it was cracking and falling off.
3) 90-degree romex became readily available.
From a practical standpoint, if you're replacing a fixture with a similar one, or one that keeps the heat farther from the wiring than the old one, and if the insulation on the existing wiring is sound, you can safely (if not legally) install the fixture, even on 60-degree wiring.
If the above isn't true (or you want to be perfectly legal) then the ideal thing, if there's an attic above, is to install a junction box and run 90-degree wire into the fixture box. If no attic (or other easy way to install the junction box) then you need to either pigtail the wires real close to where they enter or sleeve them. Either of these is of questionable legality but should be reasonably safe.
Also, of course, NEVER install larger lamps than the fixture is rated for.
happy?
Nicely said. My electrician (a real stickler for code) won't install any new fixture that says 90 degree wire only in a house older than 1975 unless he can confirm the rating of the wire. Its a good thing he is about to retire. It does seem that if all new fixtures need 90 degree wire and people install them anyhow never caring one way or the other then houses should be burning down all around us. Do you feel the heat?Mother nature will out live us all.
Thank you! This is in an attic where the peak is not far from the fixture, so I will probably put a junction box in just to keep whatever wire is there separated from the part of the circuit where the fixture is. I plan on running a couple of fixtures off that, so I can run new romex to them from the junction box. I appreciate everyone's input. This site rocks!
The "NM-B" designation would be on the outside jacket of Romex. If you see printing on individual wires, the letters to look for are: THHN, THHW, THW-2, THWN2, OR USE-2. They all mean 90 Centigrade.
-- J.S.
It will say on the conductor insulation. Thhn is the coin of the realm now. It is most often 90deg Centigrade rated. Lately, common brands of single conductors are rated 105. Check the writing on the wire for accuracy.
The cloth covered rubber or neoprene insulation found in SO wire is generally lower temperature.
All new installations or houses made in the last 40 yeqrs ought to have 90 degree wire. But like the other writers suggest... check.