To determine which of the two conditions exist, disconnect the tip side of the pair under test, and test
again. If a click is heard, the fault is a cross. If no click is heard, the fault is a short circuit.
NOTE: A faulty pair should be tested for grounds before it is tested for short circuits because a
ground on either side of the line may cause an improper diagnosis of the fault.
c. Clearing Shorts From Line. The exact location of a short in the open, drop, bridle, or inside
wiring may be found by visual examination. If this is impossible to perform, or if the wiring is damaged
or deteriorated, replace the wiring and rerun or reroute the wiring, or reinforce the insulation, as
Most line grounds occur at the substation protector. This is caused by pitting of the carbon
blocks when high voltages arc across the .003-inch gap, causing the blocks to make contact with each
other. Dust particles settling between the carbon blocks will cause them to make contact with each
a. Causes of Line Grounds. Line grounds are caused by the following:
(1) Bare conductors of a worn deep wire which make contact with any grounded metallic
object will often result in an intermittent ground.
(2) Wet or worn inside wiring which makes contact with a grounded metallic object.
(3) A broken braid at the terminal can which makes contact with the terminal, cable stub, etc.
b. Testing for and Locating Ring Ground.
(1) The term ring ground refers to an undesired electrical connection between the ring side of
a working line and ground. The first step in locating this fault is to determine the portion of the circuit
in which the fault lies (in the distributing cable, drop, protector, inside wire, or telephone set). When
practicable, the tests should begin at the connecting box.
NOTE: Assume that the fault is at the telephone set, that the first test is being made at the connecting
box, and that a protector is used in the circuit.