Help:Locating break in electric cable

boblalux · Feb 5, 2017

I am often called upon to help people with, for example, a vacuum cleaner which no longer works. First thing I do, I check continuity of the live and neutral wires between the plug and the machine. Most of the problems are just of a continuity nature along the 10-20 foot cable, but where? , Not always at the ends. Just cutting in the middle, and checking both ends for continuity, is pretty destructive. Until now, I use a pin to pierce the wire covering and measure for continuity, and test the continuity until I find it, therefore not having to cut the cable unnecessarily. Works fine, but I don't like the fact that there are now a number of tiny holes in the wire covering. Is there any better method? I tried using a compass to see if there is only a swing in the live portion of the wire, butdoesn' seem to work.
HELP

Chemelec · Feb 5, 2017

Repairs at each end is Ok.
But since it is Not really Practical to SPLICE a cable somewhere in the middle, Why not Just Replace it.
And Probably the SAFEST WAY.

Alec_t · Feb 5, 2017

Personally, I'd cut off about 10-20 cm from each end and test the remainder for continuity. If no continuity then I'd scrap the cable, on the basis that the wires have probably been stressed so may not be safe to use (through work-hardening, embrittlement, partial fracture).
Even if you could locate a break part way along the cable the only fix would be to use a cable connector. That in itself would not be ideal, because it could snag on obstructions when the appliance is in use.

KTW · Feb 5, 2017

Search for opens tester.

duke37 · Feb 5, 2017

Give each wire at both ends a yank and if the copper is broken near the end, the insulation will stretch.
Look for any twists in the cable. Make sure that no twists are made when the cable is used, I use two supports with the cable wound in a figure of eight around them.
I have made an oscillator using a CMOS 4093, set to run in the medium wave. I have used this with a small portable radio to find a junction box under the floor, the location of a cable running underground from a shed and breaks in christmas tree lights.

boblalux · Feb 6, 2017

duke37 said:

Give each wire at both ends a yank and if the copper is broken near the end, the insulation will stretch.
Look for any twists in the cable. Make sure that no twists are made when the cable is used, I use two supports with the cable wound in a figure of eight around them.
I have made an oscillator using a CMOS 4093, set to run in the medium wave. I have used this with a small portable radio to find a junction box under the floor, the location of a cable running underground from a shed and breaks in christmas tree lights.
Click to expand...

Good idea, I'll try this. Only problem is that on a number of occasions, it is only one of the 2 wires (live or neutral) which is broken

duke37 · Feb 6, 2017

If one wire is broken, then the others are near failure. Cut off a considerable amount to get to a good part.

The main problem is that the earth wire could be broken or near broken without any indication.

Teach the operator to treat cables with care. Bend as lttle as possible and use a large radius.

boblalux · Feb 6, 2017

duke37 said:

If one wire is broken, then the others are near failure. Cut off a considerable amount to get to a good part.

The main problem is that the earth wire could be broken or near broken without any indication.

Teach the operator to treat cables with care. Bend as lttle as possible and use a large radius.
Click to expand...

Good idea. But try and teach your nearest and dearest, not to yank the vacuum cleaner cable but rather the plug, when finished (by the way, I as husband, also use it).

Help:Locating break in electric cable

boblalux

Chemelec

Alec_t

KTW

duke37

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duke37

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