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Discussion Forum

Light Fixtures and Wire Insulation –…

| Posted in General Discussion on January 28, 1999 08:12am

*
We have a home built in 1981 and are in the process of replacing many of the late 70’s, early 80’s light fixtures with updated versions. I am removing the “globe” light over the kitchen sink and putting in a Can, and putting up new brass hallway fixtures, to replace those globes.

All of the packages have warnings all over them about wire insulation needing to be 75 to 90 degrees Celsius. Our supply wires are UL AWG 14 Type NM, 600V, and UL AWG 14/2 Type NMB, 600V. All wires have bare copper grounds running through the middle. They appear to be exactly what’s sold in the home stores today. (same thickness, color, etc..) No one at the store can tell me how to find the temperature rating.

Our Can light is an IC housing rated for 75 watt bulb. We are using a 65 watt bulb and there is no insulation in the section where the light will go. The hallway fixtures are just glass octagons with 4 – 40 watt bulbs.

Can someone please tell me about wire insulation temps and what they mean? Also, how I may be able to tell what we have?

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Replies

  1. Guest_ | Jan 19, 1999 06:10pm | #1

    *
    If the NM cable has a B stamped on the wire code, usually after the NM it is for 90 degrees. If there is no B, 60 degrees.

  2. G.LaLonde | Jan 19, 1999 06:42pm | #2

    *
    Brent, I would be very surprised if you had 90 degree wire anywhere in your home. Another way to tell the difference is to look at the black / white insulation that covers the individual wires. Get a piece of cable that you know to be 90 degree and look at the black/white insulation. It is pretty thin and hard and has a shiny coating on it. The older wires were covered with a much thicker dull colored insulation. What does all this mean????

    I have seen a lot of melted down insulation in fixtures with the old cable. These were can lights or lights where the bulbs were completely enclosed by a globe. Usually someone installed a bulb that exceeded the recommended wattage.

    In your particular case, I would install the IC light (if it has a remote wiring box) and is not covered with insulation. I would not feel comfortable with any light that completely encloses the bulb. It is too easy to make a mistake and install the wrong (too big) bulb.

    That old insulation definitely does melt!! The warnings on these light fixtures are valid. Proceed with caution.........

    1. Brent_ | Jan 19, 1999 07:05pm | #3

      *Thanks for the response, I was afraid the "no B" would mean only 60 degrees. Do you know exactly what this rating is measuring? I imagine that it's saying if the temp inside the junciton box exceeds 90 degrees celsius, the insulation will melt and that can cause sparks. I am mostly concerned about our CAN light, which says a 90 degree minimum. As I mentioned, the IC CAN will be sitting in an open, uninsulated area, and have a 65 watt bulb, versus the 75 watt allowed in the fixture. It has a remote junction box (about 8-10 inches from the fixture). The wires going to the kitchen are stamped only NM.

  3. Guest_ | Jan 27, 1999 06:54am | #4

    *
    I'm surprised that you'd have to worry about heat with a detached junction box... If it is gets up to 90 degrees -- about 200 degrees Farenheit -- it's not the sort of thing I'd want stuffed in my ceiling. But it pretty much routine for light fixtures to require the newer wire, though I doubt most people pay any attention. As I said earlier, before the computer gods frowned on this board, the risk of fire in an overlamped fixture is very, very real.

    I suggest, as before, energy-efficient lighting. It will reduce your electric and A/C bills. The 4x40-watt fixtures produce only as much light as about one 100-watt bulb. But this may be infeasible; if you want to stick with 95% inefficient incandescent installed in a fixture that will duct warm air out of your home, and are still worried, just install splice at a safe distance, perhaps with a little fan and a heat shield ... :) ... then run modern wire to the fixture. The junction box needs to be "accessible"; I think you could put it in the ceiling cavity since your easily-removable retrofit can will allow easy access. But your wire is probably fine -- call the manufacturer if you doubt it.

  4. J_Wells | Jan 27, 1999 11:24am | #5

    *
    Brent,

    The code has three temp. ratings in Table 310-16 - Allowable Ampacities: 60, 75 and 90C.

    Table 310-13 of the NEC covers the temp. ratings of various conductors. The table will tell you the trade name, the type letter (look for this stamped on the wire, the max. temp., application provisions and all sorts of other stuff.

    Example - THHN: heat-resistant thermoplastic, "THHN", 90 dgs C or 194 dgs F., dry and damp locations, flame retardant, heat resistant thermoplastic, etc.

    You might want to wire with this stuff. Melting the insulation off the conductor is a Bad Career Move. Who needs an electrical fire?

  5. Brent_ | Jan 28, 1999 08:12pm | #6

    *
    We have a home built in 1981 and are in the process of replacing many of the late 70's, early 80's light fixtures with updated versions. I am removing the "globe" light over the kitchen sink and putting in a Can, and putting up new brass hallway fixtures, to replace those globes.

    All of the packages have warnings all over them about wire insulation needing to be 75 to 90 degrees Celsius. Our supply wires are UL AWG 14 Type NM, 600V, and UL AWG 14/2 Type NMB, 600V. All wires have bare copper grounds running through the middle. They appear to be exactly what's sold in the home stores today. (same thickness, color, etc..) No one at the store can tell me how to find the temperature rating.

    Our Can light is an IC housing rated for 75 watt bulb. We are using a 65 watt bulb and there is no insulation in the section where the light will go. The hallway fixtures are just glass octagons with 4 - 40 watt bulbs.

    Can someone please tell me about wire insulation temps and what they mean? Also, how I may be able to tell what we have?

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