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Aluminum Home Wiring


Published: 07/04/2013

by Sean Duggan

During this period, aluminium electrical conductors (ALU) were extensively used as a more cost effective means to wire a house - as opposed to copper conductors. However, aluminium has certain properties which can be a concern for some insurance companies, and which a home owner should be aware of.

One of the properties of aluminium is that it expands and contracts to a greater degree than copper does. As such, connections inside junction boxes, receptacles, switches, etc. can become loose over time (particularly if connections were tenuous to begin with), causing a potential for electrical arcing, and a risk of fire.

Another property of aluminium is that all other materials used on such circuits (switches, receptacles, etc.) should be rated for use with ALU. Using improperly rated materials can create oxidization leading to excessive resistance at our connection points. Resistance equals heat, and heat equals fire.

Aluminium by nature has slightly greater resistance than copper, which will require conductors to be of a larger gauge. For instance, where a 14 gauge copper conductor is needed on a circuit, a 12 gauge ALU conductor would be needed to do the same job. In addition, the material is more brittle than copper, so care should be taken when handling ALU to ensure cracking does not occur at bends and twists in the conductor.

It should be noted that there is nothing intrinsically wrong with aluminium wiring, as long as it is treated properly. Although it is no longer installed in residential branch circuits, there is no requirement to remove it from the home. In fact this material is still routinely used in commercial wiring, and as main supply conductors. Generally the approach to dealing with ALU wiring, and what many insurance companies will require, would be to "pigtail" connections. This involves treating ALL connection points (switches, light fixtures, junction boxes, etc.) on the ALU circuit with an anti-oxidant, then using a special ALU/CU connector to add a short length of copper to the end of the aluminium wire. This process ensures that connections have good integrity today - and will remain so in the future.

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