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How to recognize or identify aluminum electrical wiring in buildings. This article provides tips and photographs helpful in identifying the presence of aluminum wiring in residential 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 closeups of aluminum wire in various applications.
How to Recognize or Identify Aluminum Electrical Wiring in Homes
Watch out: unless you are specifically trained to do so, 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 shock.
[Click to enlarte any image]
When was the house built or re-wired or when were circuits added?
Homes 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.
An electrician or home inspector qualified to open the electric panel
will look at wire at circuit breakers in the
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
Also notice the 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 itself.
Look for the word "Aluminum." Without opening any electrical panels or other devices, a homeowner or building inspector can still 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
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, aluminum wiring may be present. 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 and since #14 copper wire branch circuits are common in homes, 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
Where wiring is visible in the attic or basement, examine the insulation for markings that indicate
the use of aluminum, such as "KAISER," "ALCAN," "ALUMINUM," or "AL/2." If you see #14, or 14-gauge wiring, that particular wire
is unlikely to be aluminum, unless someone did something
quite unusual for residential construction.
Aluminum wires spliced together in this metal junction box has not overheated. It was exposed by an electrician. A homeowner should
not be taking the risk of opening and exposing electrical wiring.
Aluminum wiring spliced to stranded copper wire in a ceiling light fixture was found during a wiring survey I performed - a common condition.
COPALUM Copper-to-Aluminum Pigtailing repairs may be observed in homes where this special AMP (now TYCO) COPALUM connector and special tool
were used to
connect short copper wires to aluminum wire ends in the building. The TYCO COPALUM connector method is described at
PIGTAILING USING AMP "COPALUM" CONNECTORS
Typically this approach costs about half that of completely re-wiring a home with copper.
AlumiConn connectors and aluminum wirealuminum to copper lug connectors used for pigtailing or splicing
may be observed in homes where aluminum wiring repairs have begun
after about June 2007.
[New in 2006, U. L. Listed, 2007 completed independent testing], recommended by CPSC 2011.
Scotchlok 3M Repair Method [- Superceded by new alternate repair as of June 2007 -] was previously recommended, prior to successful testing of the AlumiConn
(see AlumiConn and COPALUM methods introduced at ALUMINUM WIRING REPAIR METHODS).
The Ideal 65 Purple Twister, A Not-Recommended "Repair" attempt for aluminum wiring using a twist-on connector was evident in this electrical panel.
When I found this condition
I suspected, and then confirmed that the worker who tried this approach did not follow CPSC recommendations, used an inappropriate connector which has a record
of fires, and further, had failed to find and repair any of the splices in junction boxes in the building. Work like this is done by someone who has
heard vaguely about "copper pigtailing" but has not become well informed on the topic. In my opinion, an improper or partial "repair" can in such cases actually
increase the risk of overheating and fire.
Overheated, burned multi-strand aluminum wire in this electric panel confirms that even contemporary practice of using
multi-strand aluminum wiring in buildings, typically for single-use circuits like air conditioning, electric ranges, or clothes dryers, is
still vulnerable to burnouts.
Also see COPPER-CLAD ALUMINUM WIRE (safe in homes) where we distinguish among copper-clad aluminum wire, plated copper wire, and CU/AL or COLAR devices.
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ALUMINUM WIRE REPAIR METHODS to reduce risk in buildings with Aluminum Electrical Wiring - Overview of Acceptable Repair Practices (in the document you are presently viewing)
Reducing the Fire Hazards in Aluminum-Wired Homes, Jess Aronstein, Ph.D., This document answers most technical questions about the hazards and remedies of aluminum electrical wiring. Some of the sections of this very thorough document are listed below:
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