Aluminum Wiring

In the late 1960’s and early 1970’s copper prices rose and contractors/electricians switched from copper to lower costing aluminum wiring. Although no longer used in distribution circuits (the small wires in a house or condo that carries electricity to the plugs and switches), aluminum wiring is still used today in certain applications. For example, 240 volt circuits for stoves and dryers. It sometimes is used on the main service entrance wire from the road to the house.

The conductivity of aluminium is not as good as copper so thicker gauge wire was used. For example, today the most common copper wire size is 14 gauge. The comparable aluminium wire size used was 12 gauge.  Concerns with this type of wiring have arisen, for example, when aluminium wire is connected to receptacles and switches which were not designed for aluminium, or, when aluminium and copper wires are attached.  In these cases a reaction can occur causing the connections to fail, perhaps become disconnected, and potentially overheat, spark and catch fire.  Symptoms of this can sometimes be seen in the discolouration of receptacles, flickering lights, or the smell of hot plastic insulation.

Aluminum wiring in residential installations will operate as safely as any other type of wiring if the proper materials are used and it is installed as per the manufacturer’s instructions and the Canadian Electrical Safety Code.

In short, according to the Canadian Electrical Code………

If you want to use NON-CO/ALR switches and receptacles then copper pigtails are recommended.  Where aluminum and copper wires are connected, proper paste/flux, and the appropriate wire connectors, are used.

If you want to connect the aluminum wire to a switch or receptacle without pigtails, then  CO/ALR devises are recommended.

Regarding Insurance

Quote from the Insurance Bureau of Canada Web site. (

“Houses with aluminum wiring are generally safe. The principal area of concern is at connectors and receptacles. When aluminum wiring was originally installed in homes, the same receptacles and connectors were used as for copper wire. The connections can become loose and overheat, possibly causing a fire.

What do you do if you have Aluminum Wiring?

If a home has aluminum wiring and you suspect problems may exist, further professional advice from a qualified electrician, experienced in repairing aluminum wiring concerns, is recommended.

Aluminum wiring is not handyman-friendly. If you suspect anything unusual, have a licensed electrician work on circuits with aluminum wiring.

Who can do the work?

  • Buckle Electric, Victoria, 250-475-3500

Most electrical wire is made of copper. Copper is predominately used in residential construction with the exception of the service cable and single purpose high-amperage circuits such as sub-panels, electrical ranges or air aluminum wire must be larger to safely carry the same current as copper

Some houses built or remodeled between the early 1950s and late 1970s were wired with aluminum . This wiring can be identified by the letters AL or the word ALUMINUM stamped on the plastic covering or cable. Don’t confuse the brand name ALCAN with solely aluminum wiring. Alcan makes both copper and aluminum wiring for residential purposes.

There are basically three reasons why aluminum wiring may be of concern:

  • it has a tendency to oxidize which increases the wire’s resistance resulting in the wire overheating at the receptacle
  • it is more malleable (softer) than copper and therefore easily nicked
  • because of its high thermal expansion, it has a tendency to change shape at the terminal screws and thus become loose or creep off

Given its incompatibility with fittings designed for other metals in the electrical system, improper connections may cause electrical resistance which in turn may cause overheating and fire. To overcome the incompatibility, the aluminum wiring may have been “pigtailed” with copper using proper connectors, (Marrette-brown; Ideal-purple)

Warning signs of unsafe Aluminum Wiring:

  • unusually warm or warped outlets and switch cover plates
  • smoke or sparks coming from receptacles and switches
  • strange odors in the area of receptacles and switches
  • untraceable problems with plug-in lights and appliances
  • periodic flickering of lights

Care to be taken with Aluminum Wiring:

Do not overfuse aluminum wiring. The AWG (American Wire Gauge) rating of #12 aluminum wiring is equivalent to #14 copper wiring. Both are rated for 15 amps, so use only the 15 amp rated glass fuse, cartridge fuse or breaker for aluminum wiring stamped either 12/2 or 12/3.

Copper and Aluminum should never be connected together except using special anti-oxidant paste and crimped with approved clamp connectors. If you use twist-on connectors (wire-nuts or marrets) make sure they are approved for use with aluminum wiring.

When purchasing replacement receptacles, switches or fixtures ensure that they are compatible for aluminum wiring. Typically, receptacles that are approved for aluminum wiring will be stamped CO\ALR, CU-AL or AL-CU indicating they can be used for both copper and aluminum.

Do not use receptacles stamped with AL and a line through it. These receptacles are incompatible with aluminum wiring.

As part of your preventive maintenance plan for the home, check switches and receptacles by removing the cover plates and visually inspecting the wires for any signs of scorching, looseness, heat and/or odor.