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Subject: TWL: RE: Electrical Cable Fire
From: Arild Jensen (elnav@XXX.XXX)
Date: Sat Dec 28 2002 - 18:23:46 EST
-----Original Message-----
Subject: TWL: Electrical Cable Fire
I am wondering how factory made, one piece 50 amp cables & connectors are
made:
Other than the cable flexing which might have broken strands in wires,
anyone
have experience in what causes these to fail? Are they made with the usual
wire inserts into a clamping terminal with turn down screw like replacements
or is some other connection typical?
Rob Brueckner
REPLY
About 20 years ago I recall hearing about a movement to call for spot welded
cable terminations, especially in molded cable ends.
At the time I was designing and building factory production test equipment
for the likes of GE and Motorola and Philco Ford.
I recall seeeing how spot welded cable ends were placed in cavity molds then
having thermoplastic injected into the cavity to from a molded plug or
socket.
This technique provides a positive connection which will not sufffer from
loose screws; but as Rob points out, normal wear an result in broken strands
which in turn will cause a high resistance hot spot.
The only practical test is to check for higher than normal ( red ambient)
temps.
Yet another application for a hand held infra-red thermometer.
Just recently I found a fuse block measuring five degrees under the boiling
point of water despite having only three amps passing through it.
regards
Arild
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