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From: kitty!larry@uunet.uu.net (Larry Lippman)
Newsgroups: comp.dcom.telecom
Subject: Telephone Humor & Insulation Testing
Message-ID: <9765@accuvax.nwu.edu>
Date: 15 Jul 90 04:33:23 GMT
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X-Telecom-Digest: Volume 10, Issue 487, Message 11 of 11


In article <9677@accuvax.nwu.edu> ah0i+@andrew.cmu.edu (Andrew A.
Houghton) writes:

> In brief, I have heard that at one time AT&T sent out "cleaning
> pulses" in the wee hours of morning to "fuse shorts in the line."

	Reminds me of the "telephone pranks" friends and I used to
pull while in college - like calling people at random, pretending to
be from the telephone company, and asking them to place their
telephone handset in a bucket because the telephone company was going
to "purge moisture from the telephone cables."  A surprising number of
people actually fell for this.  I digress, but the best one was
pretending to be from the city sewer department, claiming that there
was a sewer collapse, and asking people not to flush their toilet for
24 hours.  The clincher on this one was eliciting cooperation by
stating: "Now we can't stop you from flushing your toilet, but think
about us sewer workers below trying to fix the problem..." :-)

> Assuming this is drivel, is there any basis for such a thing?

	The statement you quoted is nonsense, but there are two
factual elements which could contribute to its basis.

	The first is that ALIT (Automatic Line Insulation Testing) is
performed during early morning hours when telephone traffic is at a
minimum.  In both this forum and sci.electronics, ALIT has been
previously discussed because it sometimes causes a "chirp" on cheap
electronic telephones.  ALIT is strictly a passive measurement
procedure.

	The second is that there is a troubleshooting procedure used
to localize high-resistance cable faults on pulp cable using a
"breakdown test set".  A pair with a high resistance fault is isolated
from the CO apparatus and a current-limited voltage of approximately
600 volts DC is placed on the pair.  This voltage is usually enough to
cause an arc and turn a high resistance fault into a dead short -
making it easier to localize.  With improved test apparatus such as
TDR's, breakdown test procedures are no longer used as frequently as
in past years.


Larry Lippman @ Recognition Research Corp.  "Have you hugged your cat today?"
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