From the mid 1960s to the early 1970s, builders and electrical contractors installed single-strand, branch circuit aluminum wiring in some homes rather than copper wiring as a cost-cutting measure.  Tests have demonstrated aluminum wiring has inherent properties that make it more susceptible to fires when not installed correctly.  According the U.S. Consumer Product Safety Commission, reported fires and deaths have been linked to the hazards associated with aluminum wiring.  CPSC research shows that “homes wired with aluminum wire manufactured before 1972 are 55 times more likely to have one or more connections reach “Fire Hazard Conditions” than is a home wired with copper.”  Post 1972 aluminum wire is also a concern.  Introduction of the aluminum wire alloys in 1972 did not solve all of the connection failure problems.

An inherent problem with aluminum is that it does not conduct electricity as well as copper, therefore generating more heat.  When aluminum wiring warms, it expands, when it cools, it contracts.  Unlike copper, when aluminum goes through a number of warm/cool cycles it loses a bit of tightness in connections.  Arcing may occur in loose connections, causing very hot conditions in switches, receptacles and fixtures.  Worsening the condition, aluminum oxidizes, or corrodes when exposed to atmosphere and when in contact with certain types of metal.  This oxidization removes the pure aluminum and makes the wire thinner, which creates more heat when electrical current runs through it.  Aluminum oxide is a very poor conductor and creates more heat-building resistance to current.

Only two remedies have been recommended by the CPSC: discontinued use of the aluminum circuit or the less costly option of the addition of copper connecting "pigtail" wires between the aluminum wire and the wired device (receptacle, switch, or other device). The pigtail connection must be made using only a special connector and special crimping tool licensed by the AMP Corporation.

A home with aluminum wiring should be examined, its condition evaluated, and remedies recommended by a qualified and licensed electrician experienced with aluminum wiring.

More information on aluminum wiring can be obtained on the Internet at:
http://www.cpsc.gov
http://www.inspect-ny.com/aluminum/alreduce.htm
http://www.hsb.com/thelocomotive/Story/FullStory/ST-FS-ALUM.html

Aluminum wiring can be identified
by its silver-gray color