New light fixture question...?

Question

I put in a new light fixture that took me forever. Afterward (duh), I read the packaging and it cautioned that homes built before 1985 may not have the wiring to withstand the heat of the bulb which conducts 90 degree heat. It goes on to say most homes built before 1985 are only wired for lights that emit up to 60 degrees of heat. My home was built in 1981. The wires in my attic read 600 watts. Is that enough to withstand the new light fixture? If not, besides taking it down, is there anything I can do to fix this problem and not burn the place down?

It came with a 30 watt round flourescent bulb.

Yes, 600 volts, not watts. Sorry.

Answer 1

I suggest you read the bulletin in the link below. The National Electrical Code in 1984 raised the temperature rating for insulation used on type NM cable (commonly called "Romex") from 60°C to 90°C. The new cable with the higher temperature rating has been given the designation NM-B. If you look at the outside jacket of your cable, it should be identified as either type NM or type NM-B, corresponding to 60°C or 90°C insulation.

The problem is that recessed light fixtures are now days often surrounded by fiberglass or other thermal insulation, causing the heat from the light bulb to be trapped in the fixture and raising the inside temperature. Whereas 60°C wiring was once considered adequate when light fixtures were ventilated, the code now assumes that there is no air circulation in the fixture, requiring a higher temperature wire.

Of course, using a smaller wattage light bulb or a florescent bulb will produce less heat, and so the temperature will be lower. The problem is, you should allow for the worst case temperature when the fixture is operated within its rating, which may allow a 60 watt bulb or higher. The solution offered in the bulletin below is to put a junction box 18" away from the fixture, and then to run the last distance with NM-B cable.

Answer 2

Initially I agree with answer number one, but would add that it largely depends on the fixture and it being able to accept a size of screw in florescent bulb. They are however the best way to go if possible.

My issue with what you stated, and not directed at you at all, is the temp that is claimed, or perhaps the way The manuf. stated their disclaimer. I'm not suggesting YOU or anyone else touch a light bulb, especially after it's been burning for awhile, but I have to say 90 or 60 degrees is highly unlikely unless it's a night light bulb. A 100 watt or even a 60 Watt bulb can burn you. If a light bulb feels warmer than your body temperature then it's HOT!

Another issue that may be the reason for the disclaimer is if the fixture and the "Globe" etc. actually enclose the light bulbs. I just replaced a fixture that was pricey and nice looking, and stated 2, 60 watt bulbs could be used, and was totally enclosed. I replaced it after I heard the globe crack and fall to the floor the other day. The foil reflective sheilding was also flaked off the inside of the fixture base.

I will add one more thing, and I suspect it was never a life threatening risk. I have used higher watt bulbs in fixtures clearly stating "Don't" and never had a problem.

Steven Wolf

Answer 3

You are fine! The wire you read is not rated in watts but is a standard 600 volt rated wire insulation. Also the thermal rating of 90 is in Celsius and typically refers to wiring within 3" of a ballast (which is factory wired) or wiring that goes from a ballast to a HID lamp (high intensity discharge) screw shell. You are WELL within the temperature range. Imagine a house rates with 60 degree F wiring. Your house would have an electrical fire every summer, and if you warmed your house to a comfortable level it would have elec fires in winter too.

Answer 4

As long as you stay with the 30 watt bulb you should be fine. It is the wires insulation which has the heat ratings, in Celcius. I will assume the wire in you attic is marked 600V not watts, the temp rating effects allowable ampacity more than any spicific type of fixture. Most times.

You can do drawn out calculations, but you should be fine, as long as the light was installed correctly.

Answer 5

usually they just say things like that so you will have to buy new wires and stuff from that same company, just last summer we installed new lights in a building that was built in the 1920 and got wired in the 30's they work fine so it shouldn't be a worry but to be smart call up a electrision and ask but if he or she is saying O no you got it all wrong I can come fix it for you they more in likely lieing trying to get your money. if anything and you still feel unconfertable go bye a new one made for copper wires, thats why they changed. copper wires was allowed intill 1985 but they cause fires in genaral so if you want to feel safe get a new light fixture or string a new wire to your light from the braker box.

if its a floresant light you don't have to worry because floresant lights don't get hot enuf to do anything.

Answer 6

If your house was built in the 80s you are fine. If you don't feel safe with that, use flourescent bulbs (which is a good idea anyway). They run a lot cooler and also save you on electricity.
BTW, I am a master electrician so you can trust my advice on this.