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Aluminum Wiring in
Residential Buildings

Aluminum electrical wiring was installed in some houses and multi-family buildings as early as the mid 1960s, but mostly during the 1970s.

The Problem:

There were several generations or types of aluminum wiring, but in general the solid aluminum wires are all considered to increase the chances of an electrical fire by a substantial factor… the American Consumer Products Safety Commission estimates that the older types of aluminum wiring are 55 times more likely to cause fires than standard copper wire.

burned outlet
The problem is not with the aluminum wire itself, but at connections. This is a picture of an actual AC outlet that caught fire when the aluminum wiring connected to it overheated the outlet terminals. This can be prevented with the proper use of an antioxidant paste on the wiring and connections at installation or retrofit time.

There appears to be a number of factors that all contribute to the increasing fire hazard:

Do You Have Aluminum Wiring?

If the electrical wiring is visible in the attic, basement, or crawl space, the outer covering will be marked "ALUMINUM", "ALUM", "AL", "ALUM ACM", or "AL ACM". You can also have an electrician inspect the main electrical panel.

Note that in modern construction, the main service cable, the wiring for the electric stove and electric clothes dryer will often be stranded aluminum cable. This is not considered a fire hazard when properly installed and the connections protected with antioxidant paste.

Some Warning Signs:

Reducing Risk:

The earliest recommended upgrades in both Canada and the USA required replacing the existing switches, outlets, lamp bases, etc. with "CU-AL" rated devices. This was not effective and CO/ALR devices were developed.

In the United States, the Consumer Product Safety Commission has determined that only "pigtailing" copper wires to the ends of the aluminum wires with a metal crimping device (AMP COPALUM Method) is acceptable.

In Canada, it is considered acceptable to "pigtail" copper wire to the aluminum with CSA-rated twist-on wire connectors and an antioxidant compound. It is important that a clean and tight connection be maintained between the copper and aluminum surfaces, otherwise the metal coil inside the wire connector can carry electricity and fail.

It is important to note that while aluminum wiring is still allowed by the Canadian Electrical Code, the "pigtailing" method is not specifically addressed. Regulations can be expected to change with additional research and the push by various interest groups to make housing safer.

More information:

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