Aluminum wiring that is installed correctly and has been correctly maintained is acceptable, however wiring is often neglected and neglected aluminum wiring is a potential fire hazard.

Aluminum Wiring Hazards

Between 1965 and 1973 aluminum wiring was sometimes substituted for copper wiring in residential electrical systems.

Connections in outlets, switches and light fixtures with aluminum wiring become increasingly dangerous as time passes. Poor connections cause wiring to overheat, creating a potential fire hazard.

In addition to creating a potential fire hazard, the presence of aluminum wiring may have an effect on your insurance policy. You should ask your insurance agent whether the presence of aluminum wiring is a problem that requires changes to your policy language in order to ensure that your house is covered.

Options for Correction

The wiring should be evaluated by a qualified electrician. This means an electrician experienced in evaluating and correcting aluminum wiring problems. Not all electrical contractors qualify.

At the minimum all connections should be checked and an anti-oxident paste applied. Other options are splicing copper wire at the connections (called "pigtailing", not a great option) and copalum crimps which, although they are the safest option, are expensive (around $50 per outlet and switch).

Here are the reasons aluminum wiring connections deteriorate:

 Thermal expansion and contraction:
Even more than copper, aluminum expands and contracts with changes in temperature. Over time, this will cause connections to loosen.  When wires are poorly connected they overheat, which creates a potential fire hazard.

 Vibration:
Electrical current vibrates as it passes through wiring. This vibration is more extreme in aluminum than it is in copper and as time passes, it can cause connections to loosen. Again, when wires are poorly connected they overheat, which creates a potential fire hazard.

 Oxidation:
Exposure to oxygen in the air causes deterioration to the outer surface of wire. This process is called oxidation. Aluminum wire is more easily oxidized than copper wire and as time passes, this process can cause problems with connections. Again, when wires are poorly connected they overheat, which creates a potential fire hazard.

 Galvanic corrosion:
When two different kinds of metal are connected to each other a very low-voltage electrical current is created which causes corrosion. Corrosion causes poor connections.

More information is available at this comprehensive website. http://www.inspect-ny.com/aluminum/aluminum.htm

Some homes with basements, crawlspaces or attics which provide good access may be re-wired at a surprisingly reasonable cost. Other homes may be very expensive to re-wire.