Rev. 11/10/00
6
Crosses
A cross occurs whenever a Tip or Ring conductor of one pair touches a Tip or
Ring conductor of another pair. A battery cross occurs when a Tip or Ring
conductor in a pair touches another Ring conductor.
Splits
Splits occur when the Tip or Ring conductor of one pair is transposed with the
Tip or Ring conductor of another pair.
Power Influence
Power Influence is the noise that is present from AC inductance upon a cable or
pair. In a balanced pair, the noise due to power influence is not audible. In an
unbalanced pair, the noise is audible. Power influence is typically caused by poor
bonding and grounding of the cable shield.
Induction
Induction occurs when a changing magnetic field causes current to flow in a
wire. Telephone lines are susceptible to induction from AC circuits and other
telephone wires. Induction from AC circuits usually imparts an audible hum on
the line. Cross talk is caused by the induction from other telephone lines. In a
well balanced pair, noise is not usually heard.
Circuit Loss
Signal power lost between the milliwatt supply of the CO and the station
protector is known as circuit loss. Symptoms are: inability to call out, hear, or be
heard. Improper cable assignment, low loop current, excessive bridge taps, and
high resistance are typical causes for loss.
Loop Current
Loop Current is the amount of current in milliamps that flows from the CO
through the loop and back to the CO. Loop current is required for dial tone
requests, touch-tone pad operation, ring trip when a call is answered, and talk
battery to the transmitter. Low loop current symptoms include: no dial tone,
wrong number dials, can’t hear, and can’t answer. This is usually caused by
corroded connections, excessive loop resistance or missing range extenders.
