brittle insulation


Old 05-09-05, 09:52 AM
Thread Starter
Join Date: Dec 2004
Posts: 237
brittle insulation

went to change ceiling light in basement this morning.when i pulled the wires from the box the insulation on the white and black wire is very dry and brittle.i used white and black electrical tape to wrap the wires and went to home depot and got a 3 track light mounted on a round base light.
the old fixture had no insluation on the top,and i think the heat from the 2- 60 watt bulbs in the globe destroyed the wire insulation.does the insulation make that much of a difference,or is it cause the light get a lot of use and produces too much heat.
either way i decided to go with the track light type fixture so at least the heat from the bulbs has somewhere to go other then inside the celing box..
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Old 05-09-05, 10:15 AM
Join Date: Sep 2000
Location: United States
Posts: 18,497
If your house is pre-1985, it does not have 90-degree wire. This wire is affected by heat more than post-1985 wire. This is of course why so many fixtures contain warning about pre-1985 wire.

It could also be that even though the fixture currently has 60-watt bulbs, it might have had 100-watt bulbs earlier in its life.
Old 05-09-05, 11:18 AM
Mr Fixit eh's Avatar
Join Date: Dec 2004
Location: Ontario, Canada
Posts: 94
When you say "dry and brittle", how bad is it? If the insulation is cracking or crumbly, you should replace the run of wire. You may be able to loosen the cable clamp and pull through a little slack in the old cable. At the very least, you should make sure the electrical tape is the high quality 3M stuff for $3 a roll, not the 49cent stuff which is not heat resistant.

Old 05-09-05, 04:07 PM
Thread Starter
Join Date: Dec 2004
Posts: 237
the wiring is before is bx and in a finished ceiling,i wish i could pull a few inches through the box,but it is impossible without damaging the ceiling...i used good electrical tape and plenty of it,everything seems to be fine,i will make a weekend project soon and change the line itself....
Old 05-10-05, 06:49 AM
ElectricalMan's Avatar
Join Date: Feb 2005
Location: Harrisonburg
Posts: 744

Yes the old brittle wire has caused a many nightmare in an electricians day when replacing recepts and switches in old homes with BX cable. Been their...done that...

Another thing you can do in the future is also guy some heat shring tubes that are sold at the home and garden stores. when dealing with BX you can push the smaller heat shrink tubes over the wire and down into the BX tube itself to protect down as far as you can.

Now dont heat wrap it well about 1/2" from the end of the wire itself and it should also give you some added protecting when dealing with old brittle BX and the wire within it.

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