(5) Wiring at any point of termination extending too far and contacting another lug.
(6) Inside wiring nails driven so that the metal nail penetrates the insulation of two leads in
such a way that it makes contact with both.
(7) A pair of open wire leads having excessive slack between supports; these leads may
swing into contact during wind storms and produce a swinging short. A pair of open wire leads may
wrap around each other during a violent wind storm or as the result of a heavy impact against a line
support and remain in this position.
b. Testing for and Locating Shorts.
(1) Testing for line shorts requires a knowledge of the physical position of the line under test
with respect to other working lines. If the line under test is a single pair of open wire leads or a single
drop, bridle or inside wire pair, testing is simplified. For any one of these conditions, open either lead of
the pair at fault toward the central office or PBX, and connect the test set between the end of the lead
just removed and the terminal from which the lead was removed. If the open is made on the tip side of
the line, line battery will flow from the ring side of the line out across the short circuit, back on the tip
side of the line, through the test receiver, and back to the source. A click will be heard in the test
receiver. If no short existed, there would be no path from the ring side of the line to the tip side and no
current would flow in the test set. However, if the pair under test is one of many working pairs in a
cable, more care must be taken to diagnose properly the true nature of the fault.
(2) To test for a short-circuited pair in a cable containing other working circuits, set up the
conditions for test as outlined in (1) above with the open on the tip side of the line. If a click is heard,
either the pair may be shorted, or the tip side of the line under test may be crossed with the ring side of
another working pair. Determine which fault exists by disconnecting the ring side of the line under test
from the line toward the central office and test again. If a click is heard, the fault is a cross. If no click
is heard, the pair under test is short-circuited.
(3) Close the tip side of the line and open the ring side. Connect the test set between the
open lead and the terminal from which the lead was removed. A click will indicate either that the pair
under test is short-circuited, or the ring side of the line under test is crossed with the tip side of another
working pair.
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