ELECTRICAL FAULTS.

Press, Volume LXVI, Issue 19941, 30 May 1930, Page 4

ELECTRICAL FAULTS.

WATCH FOR "SHORTS.** Electrical faults in motor-cars are not frequent nowadays, but when they do occur they are primarily due to vibration. Wires which hang loose or sag will, under the vibration of the car, rub against metal parts of the engine or chassis. This movement and consequent friction will wear the insulation and a short circuit in the current will result. Very often this "short" is intermittent. When tested with the car at rest there may be no leakage. But when the car gets on the road the "short" is continually being set up.

This is often the cause of a discharged battery. The current perhaps in the wire from the battery to the starter switch or the lamp circuit switch "shorts" intermittently. If it is in the lamp circuit it may be discovered by flickering of the lamps when the car is running, while they burn steadily when the vehicle is at rest. Such a condition very often denotes a loose wire, which, by vibration, comes in contact with some part of the frame, becomes chafed, and allows a short circuit to occur. The remedy for these troubles lies in a proper support of the wires and proper insulation. Much of the trouble arises at places where the wires are led through holes in the frame or mudguards.

A very usual place is in the valance between the car frame and tho running, board, where the battery is carried on the latter. Tho valance is thin motal, and the hole through which the cable passes has sharp edges. These will in time cut the cable and cause trouble. This "short" may be intermittent. It may be continuous. It may not be a real "short" in dry weather, but it may become one in wet. It can set up all kinds of puzzling troubles with the lighting and starting installation, and has been known to result in what might almost bo called a "trickle" discharge from tho battery, soon running it down.