Electrical Hazards

Aluminum Conductor Facts and Myths

During the 1960s, the price of copper rose sharply due to acute shortages. The electrical industry elected to allow aluminum wiring for residential use.

Aluminum has very different properties compared to copper.  It is a much softer metal, it oxidizes more readily, and it has a greater ability for expansion and contraction. It also has higher impedance to the flow of electrons along its length. Aluminum conductors need to be sized larger than copper for any given amperage.

The Consumer Product Safety Commission (CPSC) has noted, from researching causes of electrical fires, that a home wired with aluminum conductors is 55 times more likely to suffer an electrical fault resulting in fire.

What are the issues?

Due to its softness, oxidization rate, and the ease with which it expands and contracts, aluminum wire tends to loosen up from its connection points. This ONLY affects single-strand aluminum conductors that would be found on lower amperage branch circuits. The signs of poor connectors on aluminum wiring include flickering lights, intermittent power failures at receptacles, and overheating wires.

When was aluminum used for branch circuits?

Many homes built between 1965 and 1975 had single-strand aluminum wiring.

The aluminum alloy was changed in 1972 to a higher-quality grade, resulting in fewer problems.  It is still recommended that all single-strand branch wiring be properly evaluated by a licensed electrical contractor specializing in aluminum wire repair.

Repair Methods

Since the early 1970s, several methods have been tried to improve the contact between aluminum wire and junctions and receptacles. The single biggest issue is that it is very difficult for a contractor to know where all of the hidden junction boxes are in an older home.

· re-wiring in copper: This is obviously the best choice by far, as it completely replaces the aluminum branch circuit wiring. However, this is very costly and disruptive.

· pig-tailing copper: A method many electricians tried was to pigtail a piece of copper wire, using a wire nut, onto the aluminum. There were even special purple wire nuts produced with antioxidant paste in them designed for this application. This repair did not work as intended, as wire nuts are not able to overcome the expansion problems of aluminum.

This is NOT considered an effective repair.

· CO/ALR switches and receptacles: These were designed to replace previous CO/AL receptacles, as they had a higher-quality conductor lug assembly. However, this addresses only the issues of switches and outlets, but not the connections in boxes.

This is NOT considered an effective repair.

· COPALUM connectors: These are the recommended upgrade for aluminum wiring.

A special crimp connector and crimping tool are used to pigtail a piece of copper wire onto the aluminum conductor. This is then covered with a heat-shrunk insulation.

This is the ONLY CPSC-approved repair, but some connections still may be inaccessible.