Aluminium House Wiring

Conductivity

• Copper wiring is used in modern (post-1972) buildings because copper is an excellent conductor of electricity. While aluminum is also a good conductor of electricity, an aluminum wire has a conductivity that is 61 percent of an equivalent copper wire. Because aluminum is less conductive than copper, an aluminum wire must have a larger diameter than a copper wire to conduct the same amount of electric current. For example, a 15-amp branch circuit wired with copper wiring normally requires 14 American wire gauge (AWG) wire; a 14 AWG wire has a diameter of 1.63 millimeters. A 15-amp branch circuit wired with aluminum wiring must use 12 AWG aluminum wire, which is 2.05 mm in diameter.

Expansion and Contraction Cycles

• The aluminum alloys used to make electrical wiring between 1964 and 1972 were prone to expansion when the aluminum heated up and contraction when the heated wire cooled down. These expansion and contraction cycles put stress on the mechanical connections between wires, which can cause these connections to come loose. A loose mechanical connection can cause material oxidation and overheating. These loose or oxidized wires can pose a fire hazard.

Retrofitting Aluminum Wire Connections

• Many houses that contain aluminum wiring were wired using methods that are only suitable for copper wiring. Because of this, many of the mechanical connections between aluminum wires -- or between aluminum and copper wires -- can become loose or suffer oxidation. According to the U.S. Consumer Product Safety Commission, aluminum wire connections can be made safely by means of a "Copalum" repair. This method uses a special tool and die set to make an electrical connection between an aluminum wire and a copper pigtail wire. The copper pigtail may then be connected to any electrical outlet, light fixture or switch that can be used with copper wiring.

Aluminum Wiring in Modern Buildings

• Aluminum wire as used in buildings built between 1964 and 1972 is no longer available for sale. Many of the problems experienced with this wire caused the aluminum wire industry to change the aluminum alloy in aluminum electrical wire. Most modern homes thus contain copper wiring throughout the home; but some homes may have aluminum feeder cables or aluminum service entrance conductors from the electric transformer to the fuse box or circuit breaker panel. Since the feeder cables and service entrance conductors use special connectors, aluminum wire can be used safely for these purposes if the transformer, fuse box or circuit breaker panel is designed to be used with aluminum wire.