Old building branch wire

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olc

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Have you found that:
In a building with "old" wiring where the wire insulation is cracking at a device or light fixture box, that the wire insulation is deteriorated through the remainder of the circuit?
Does it depend on whether it is in conduit or a cable assembly?
Or is the insulation worse at the box due to wear?
 
I have found that it is always much worse in an outlet box. It only takes one switch replacement, light fixture replacement, etc, in the decades between installation and me being in that same box to have cracked it up. The undisturbed cables and wires look great. That said, I live in a fairly new part of the civilized world.
 
I agree that it's almost always where the insulation is exposed in the ceiling box, due to decades of heat from incandescent bulbs. When I have worked on receptacles in the same house, the insulation is nowhere near as dry and crumbly, unless the receptacle has overheated.

My solution is to remove as mush dry insulation as I can, and to slide insulation, usually one gauge larger, I have stripped from modern NM cable over the exposed copper. I cut the insulation slightly longer, so it's held well inside the old cable by the wire-nutted connection.
 
My observations have been that the insulation's usually in pretty good shape where the outer jacket is intact. I suspect rubber insulation deteriorates faster when it's exposed to oxygen.
 
LarryFine said:
...My solution is to remove as mush dry insulation as I can, and to slide insulation, usually one gauge larger, I have stripped from modern NM cable over the exposed copper. I cut the insulation slightly longer, so it's held well inside the old cable by the wire-nutted connection.
Click to expand...

I'm going to remember that trick. I will, however, forget to give you credit when someone else sees me doing it and thinks it's brilliant.
 
I agree with Larry, it is usually much worse at light boxes due to heat of the fixture.

If it is super brittle and cannot easily be replaced, I use a heat shrink kit for electrical wiring that you can get at Home Depot for about 20 bucks. Straightening the wire out perfectly to get a piece of wire insulation over it is sometimes easier said than done.
 
JFletcher said:
Straightening the wire out perfectly to get a piece of wire insulation over it is sometimes easier said than done.
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That's why I use, say, #12 insulation on old #14 wire; goes on easily. I do make sure the colors are correct.
 
LarryFine said:
That's why I use, say, #12 insulation on old #14 wire; goes on easily. I do make sure the colors are correct.
Click to expand...

:thumbsup:

The other thing that I like to do on those older wires, which are almost always very short, is to put a Wago on them, tail in new wire pigtails, then push the old wire to the back of the box. Plenty of new wire to work with, and I do not have to disturb the insulation on the older wire anymore.
 
sameguy said:
Heat shrink.
Click to expand...
JFletcher said:
The other thing that I like to do on those older wires, which are almost always very short, is to put a Wago on them, tail in new wire pigtails, then push the old wire to the back of the box. Plenty of new wire to work with, and I do not have to disturb the insulation on the older wire anymore.
Click to expand...
Ooh, a good combination! Use black and white heat-shrink that will fit over the old insulation. :thumbsup:


If there's any left, that is. ;)
 
olc said:
Have you found that:
In a building with "old" wiring where the wire insulation is cracking at a device or light fixture box, that the wire insulation is deteriorated through the remainder of the circuit?
Click to expand...

when changing out devices or fixtures, almost always find insulation still intact outside of box, even if insulation crumbling off inside box

but a few years ago I stripped old cloth-covered scrap and found deteriorated insulation in the middle of some of the runs, figured out that those parts of runs came out from the sides of the house where the rafters met the wall plate
 
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