I have a house that was built in 1923 which has the original BX armored cable throughout. At the switches, fixtures, and outlets, some of the cloth-over-rubber sheathing has become brittle, cracked, and is falling off. I have repaired some of this with heat shrink wrap and it seems to work well. My question is, if some of the frayed cloth strands come in contact with the copper conductor under the heat shrink, is it a fire risk? In other words, when I wrap the wire in heat shrink, some of the cloth strands under the heat shrink will be touching the copper wire. Should I be concerned about it catching fire? Thanks.
Electrical – How to fix old BX wires
electricalwiring
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Many laptop cords are standardized. Where there is no external power supply, they often just need a stock AC cord such as this.
If it is three prong, it may be like this.
If it is damaged, replace it. It is cheap, available at many locations and safe. Do not repair except as an emergency measure.
However, many laptops have an AC cord (the cord that plugs into the wall) that also plugs in on the other end to a power supply (a small plastic brick). The AC wire almost always can be disconnected from the unit and the same replacement technique applies.
The AC cord is on the left, the power supply and its cord on the right.
If the AC cord is damaged, replace the cord.
If the other wire attached to this unit (the wire that goes to the computer rather than the wall) is damaged, this is much more problematic. These wires are almost always not detachable from the power supply, and they are usually proprietary (non-standard connectors). If the damage is very minor, you may be able to get away with shrink tubing, if it fits over the connector (sounds doubtful), or plastic electrical tape (always a bit sketchy on a wire that flexes). This is a low voltage wire, but it still is problematic. You may need to get a replacement power supply from the manufacturer or a third party supplier.
On the other cords, there are two types of replacement plugs, screw on and piercing.
Pierce seems easier, but screw on seems more reliable. They are also available in polarized and three prong versions. Cut the wire above the bad section and bring your old plug to match.
What you want to do is terminate the wires in the junction box using Wire Nuts. Simply thread them on to the end of the exposed wire, and you need not worry about live wires touching, kids getting zapped, etc. You should turn off the branch circuit in question (via a circuit breaker or removing a fuse) while removing the outlet and putting on the wire nuts.
If you need to have the box open for a more extended period of time, get a flat cover plate for the junction box (put on the wire nuts, tuck the wire back in the box, attach the cover plate).
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Best Answer
As I understand it, normal cloth is not electrically conductive, so it shouldn't be a significant problem if some of it touches the conductor. My bigger worry would be a failure of insulation leading to a short-circuit in the cable. Applying the heatshrink will have inevitablly involved moving the wires around increasing the chances of cracking.
I would be very wary of touching the installation any more than you absoloutely have to before you are able to re-wire it.