Copper versus Aluminum Wiring

Copper has been used in electrical wiring since the early 1800’s. It is an excellent conductor of electricity and has unique properties that make it the ideal choice for electrical wiring. When the price of copper became too expensive in the 1960’s, aluminum wiring was introduced as a less expensive alternative.

Aluminum wiring can be safe and is still being installed in new construction. Despite this, there are problems that weren’t known in the beginning. Aluminum wiring will rust, which then acts as an insulator. The wiring is also softer than copper, which becomes easier to damage when worked with. A study conducted for the US Consumer Product Safety Commission (CPSC) showed that homes built before 1972 with aluminum wiring, are 55 times more likely to have one or more wire connections at outlets reach “Fire Hazard Conditions” than homes wired with copper.

 

Aluminum Wiring Considered a Fire Hazard

The survey included only aluminum wire connections at electrical outlets. The “Fire Hazard Conditions” are mainly found at these connections. Aluminum wiring is softer than copper and the smallest cut in a wire can cause resistance. Electrical resistance then causes heat to build up. It is then possible for the overheating wires to cause a fire.

When electricity passes through any wire, it is normal for the wire to heat up and even expand slightly. Aluminum wiring also expands considerably more than copper when heated. Eventually the wire can become loose at the connection from years of expanding and contracting. This is called creeping. Once the wire has become loose at the connection, electricity may arc or spark between the gap. The arcing creates overheating, which may cause a house fire.

Despite the hazards of having aluminum wiring, it is usually impractical to rewire the entire home. While it may be preferable to replace all the aluminum wiring with copper, the benefits will usually outweigh the cost. CPSC has approved two other methods of repairs. Special connectors can be installed between the aluminum wire and the receptacle itself. Once either COPALUM or AlumiConn connectors are installed by a licensed electrician, the aluminum wiring will no longer be considered a fire hazard.