How to Recognize Aluminum
Electrical Wiring in Buildings
photographs helpful in identifying the presence of aluminum wiring in
residential/commercial properties. Because we've had requests for help in identifying this
wire we've included some tips. Be sure to also look at other photographs
available at the
Aluminum Wiring Website
as many of them show close-ups of aluminum wire in various applications.
Click on the thumbnail sketches below to see each
do not open or disassemble or touch any electrical panels, devices,
components if you are not trained and competent. There is risk of fatal electric
- When was the house built or re-wired
or when were circuits added?
buildings built, rooms added, circuits rewired or added between 1965 and 1973
may contain aluminum wiring.
- Don't assume that there's no
aluminum wire if your house was
not built during these years. Circuits may have been added, extended,
modified using aluminum wiring. Or an installer may have had leftover aluminum
wire and used it after these dates.
at wire at circuit breakers in the electric panel for aluminum wire.
The pen in the circled area points to bare silver-colored wire visible at the
circuit breaker. Notice that the aluminum wire in this photo is a single
circuit installed between two copper wires (on adjacent breakers). Also
Look at bare wire exposed at the neutral bus.
An easy place to look for aluminum wire than at the circuit breakers might be
at the neutral bus where both white neutral wires and ground wires are
connected in a row. There it's easier to see exposed portions of the wire
for the word "Aluminum." Look at for printed
or embossed letters on the plastic wire jacket where wiring is visible in the
attic or at the electric panel. Some aluminum wire has the word "Aluminum" or
a specific brand name such as "Kaiser Aluminum" plainly marked on the plastic
wire jacket. This photo shows a dark colored wire jacket with green print
indicating "Kaiser Aluminum." Some white colored plastic wire jackets are
inked in red; others have embossed letters without ink and are hard to read.
Try shining a light along the wire.
- Don't assume there's no aluminum
wire just because you find none
in the panel. Aluminum may have been used for part of circuits or for some but
not other circuits in the building.
- At outlets and switches, look at
stripped wire ends. Often simply
removing the cover plate will give sufficient view. Be especially cautious if
you see back-wired receptacles. It may be difficult to see if the wire is
aluminum, but if it is, the smaller wire contact surface when this method was
used may increase the risk of overheating or other failures.
- In the attic look at the wire gauge
or "size." Look for #12-gauge
wires in the attic or other places where wiring is readily available. If you
see only #12 and no #14, look further. Aluminum wire must be one wire gauge
size larger for a given circuit than if copper was used. So while #14 copper
wire is permitted on a 15-amp electrical circuit, if aluminum wire was used
for the same circuit it would have to be #12. Similarly, a 20-amp circuit uses
#12 copper wire or #10 aluminum wire. Common residential lighting and
electrical-receptacle circuits are 15-amp or possibly 20-amp (e.g. in a
kitchen). So if you see only #12 or larger wires in the attic of your house
look further to see if it's aluminum. The wire-gauge size is printed or
embossed on the wire jacket. #12 does not guarantee it's aluminum, it's just
more data to point in that direction.