60 vs. 90 Degrees C Wiring


Old 08-13-05, 11:46 PM
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60 vs. 90 Degrees C Wiring

I live in a 1979 house that has 60 degrees C wiring. I have been told I may replace an enclosed ceiling light fixture with one that recommends having 90 degrees C wiring if I use CFLs (compact fluorescent lamps) rather than incandescent ones.

Is this accurate advice? If not, is there a way to replace with a light fixture requiring 90 degrees C wiring without rewiring the house, which is not an option at this time.

Thank you.
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Old 08-14-05, 06:15 AM
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You have several options.

You can buy a fixture that is rated for 60 degree wire. There are some out there, but you have to look for them, and they are probably more expensive.

You can rewire the portion of the circuit containing this light. This would mean replacing each piece of wire that connects to the light back to it's next connection, or adding a junction box near the light, moving the light wires to that box and running a piece of cable from the junction box to the light. The junction box must remain permanently accessible, such as in an attic.

Last edited by racraft; 08-15-05 at 08:50 AM.
Old 08-15-05, 08:09 AM
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Is this accurate advice?
No. Use one of Bob's options.
Old 08-15-05, 09:21 AM
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The reason it is not sound advice is you can not control what some one after you might do. They could come along and use an incadescent lamp of the max rating on the fixture.
Old 08-15-05, 09:24 AM
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Should you happen to discuss this with the person who gave you the advice, be aware that from a safety perspective, they are _probably_ correct: by using a compact florescent lamp, you reduce the heat generated in the fixture, and thus lower the temperature that the wires are exposed to.

The issue is that this has not been _tested_ by UL or another 'Nationally Recognized Testing Laboratory', so the fixture will not be listed for this use, and thus you _may not_ use the fixture in this fashion if you want a code compliant installation. In theory, you could have a light fixture which was listed for 'maximum XX watts with 90C wire, maximum YY watts with 60C wire'. Also, there would be a safety issue, because nothing would prevent 'overlamping'. This is a real issue, although in many situations there is nothing to prevent overlamping with normal fixtures.

Old 08-15-05, 10:10 AM
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Compact fluorescent lamps have a very short lifespan in enclosed light fixtures. The electronics in the ballast cannot hold up to the heat build-up. Even though the CFL will not generate that much heat compared to a normal bulb, it will be enough to significantly reduce the lifespan of the lamp.

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