Wires and Cables

Wires and cables are conductors of electricity. Usually, they are made of annealed copper and are used to carry electricity to the various electrical devices and equipment on passenger cars and trucks. Wires and cables must be the right size for the application and must have proper insulation. If the wire or cable is too small in cross section or too long for its size, its resistance will be too great and valuable voltage will be lost. This will then result in poor operation of the electrical device in the connecting circuit. Wire size and length determines the resistance of the wire. Wire and cable sizes are expressed by a gauge number, which indicates the cross-sectional area of the conductor. The cross-sectional area of the wires is given in metric size or circular mils. The diameter is given in decimals of an inch. A circular mil is a unit of area equal to the area of a circle one mil in diameter. A mil is a length unit equal to .001 inches. The larger the diameter of the wire or cable, the smaller the gauge size number. Cables are made of several strands of wire. The cross-sectional area is equal to the circular mil area of a single strand times the number of strands. Special gauges are available for measuring the gauge size of wires and cables. Many multi-purpose electrician's pliers feature wire size holes for stripping, cutting, and crimping operations. When comparing cables, consider that the external diameter of insulated wire or cable has nothing to do with its current-carrying capacity. Thick insulation will make a small gauge wire look much larger. It is important that only the size of the metal conductors are compared.