Training Series: Aluminum Wiring
Hazard: Aluminum Wiring and ‘CO/ALR’ (meaning copper-aluminum, revised)
Portions excerpted from http://en.wikipedia.org/wiki/Aluminum_wire
Aluminum wiring traditionally has been used by utility companies in their large power lines because aluminum is
more durable than copper and is lighter weight and less expensive. In the mid-1960s when the price of copper
spiked, aluminum wire was manufactured in gauge sizes small enough to be used in homes. When first used in
branch circuit wiring, aluminum wire was not installed any differently than copper. Typical connections from
electrical wire to electrical devices/terminals are made by wrapping the wire around the screw terminals and
tightening them. Over time, many of these terminations to aluminum wire began to fail due to improper
connection techniques and dissimilar metals. These connection failures generated heat under electrical load and
resulted in overheated connections.
In the late 1960s, a device specification known as CU/AL was created that specified standards for devices
intended for use with aluminum wire. Because of more rigorous testing, larger screw terminals were designed to
hold the wire more suitably. Unfortunately, CU/AL switches and receptacles failed to work well enough with
aluminum wire, and a new specification called CO/ALR. CO/ALR stands for 'Copper Aluminum Revised' to
differentiate these devices from earlier models. Devices marked CO/ALR are specifically designed and approved
to ensure a good connection through the use of a larger contact area and compatible materials. All receptacles,
light switches, outlets etc connected to aluminum wiring MUST be marked CO/ALR. CO/ALR applies only to
standard light switches and receptacles; CU/AL is the standard marking for circuit breakers and larger
equipment.
CO/ALR Devices
Underwriters Laboratory lists CO/ALR devices primarily for use with aluminum wire because they use special metals at the
terminal areas that are compatible with aluminum wire .
CO/ALR marking
Loss Control: For our purposes, for buildings constructed between the 1960 through the late 1970’s
we need to be asking the question if aluminum wiring is installed. If installed, verify if switches and
receptacles are CO/ALR. If they do not meet this requirement or if we are unable to determine, we will
need to make a recommendation to have an electrician inspect and evaluate the electrical system.
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Identify if electrical is protected by circuit breakers or fuses
What is the size of the electrical service? Greater or less than 100 amps, or 100 amps etc.
Identify the manufacturer of the electrical panel
Feel the circuit breakers with your hand; they should feel cool or warm. If hot, this is a sign of
overloading/overheating. Make a rec to have this system evaluated by electrician.
If the building is built between 1960-1979, ask if there is aluminum wiring installed. If yes,
verify CO/ALR type receptacles and switches.
Verify if Zinsco or Federal Pacific brand service panels
Provide a photo of the service panel(s) in the report
There are many good websites on the internet that go into much more detail than this training brief.
One is http://ismypanelsafe.com/. Another is www.Inspectapedia.com. Of importance also is the
potential for existence of aluminum wiring. For more on aluminum wiring, see end of this brief or
http://www.eureka4you.com/home/COALR.htm and http://www.alwirerepair.com/serv02.htm for
additional insights. All of these sites were consulted for information and images on the hazards of
electrical wiring.