Aluminum Wiring in Toronto Homes: Risks, Solutions, and What to Do

What Is Aluminum Wiring?

During the 1960s and early 1970s, a sharp rise in copper prices led North American builders to substitute aluminum for copper in residential electrical wiring. Homes built in Toronto between approximately 1965 and 1978 may have aluminum branch circuit wiring — the wiring that runs from the electrical panel to outlets, switches, and light fixtures.

Aluminum wiring is still common in Toronto neighbourhoods developed during this era, including parts of North York, Etobicoke, Scarborough, and many suburban areas of Mississauga, Brampton, and Vaughan.

Why Is Aluminum Wiring a Problem?

Aluminum wiring itself is not inherently dangerous — it's used safely in large-gauge applications like service entrance cables and feeder wires. The problem is with small-gauge aluminum branch circuit wiring (15-amp and 20-amp circuits) and its behaviour at connection points.

Thermal Expansion and Contraction

Aluminum expands and contracts more than copper when it heats up and cools down. Over years of use, this causes connections at outlets, switches, and junction boxes to loosen. Loose connections create resistance, which generates heat, which can ignite surrounding materials.

Oxidation

Aluminum oxidizes (forms aluminum oxide) when exposed to air. Unlike copper oxide, which is conductive, aluminum oxide is an insulator. This means oxidized aluminum connections have higher resistance, generating more heat.

Incompatibility with Standard Devices

Standard outlets and switches are rated for copper wiring (marked "CU" only). When aluminum wiring is connected to copper-only devices, the different rates of expansion and the chemical interaction between the metals accelerates connection loosening and corrosion.

Signs of Aluminum Wiring Problems

Watch for these warning signs in homes with aluminum wiring:

• Outlets or switches that are warm or hot to the touch
• Flickering lights
• Outlets or switches that don't work intermittently
• Burning smell near outlets or switches
• Discolouration or scorch marks around outlet covers

If you notice any of these signs, call New Toronto Electric immediately at 647-642-0534.

Solutions for Aluminum Wiring

Copper Pigtailing (CO/ALR Method)

The most common and cost-effective solution for aluminum wiring is copper pigtailing. This involves:

1. 1Replacing all outlets and switches with CO/ALR-rated devices (rated for aluminum wiring)
2. 2At each connection point, joining a short length of copper wire to the aluminum wire using a special connector (AlumiConn or COPALUM crimp connector)
3. 3Connecting the copper "pigtail" to the device

When done correctly by a licensed electrician, copper pigtailing is an ESA-approved method that significantly reduces the fire risk of aluminum wiring. It's less expensive than a full rewire and can typically be completed in a day or two for an average home.

Cost: $1,500–$4,000 for a typical Toronto home, depending on the number of outlets and switches.

Full Rewire

The most comprehensive solution is replacing all aluminum branch circuit wiring with copper. This eliminates all aluminum wiring concerns and is the preferred solution for homes where:

• The aluminum wiring is in poor condition
• The home is being extensively renovated anyway
• The homeowner wants a permanent, comprehensive solution

Cost: $8,000–$20,000 for a full rewire of a typical Toronto home.

Aluminum Wiring and Home Insurance in Toronto

Like knob and tube wiring, aluminum branch circuit wiring is a significant insurance concern. Many Toronto insurers:

• Require an electrical inspection before issuing coverage
• Charge higher premiums for homes with aluminum wiring
• Require pigtailing or rewiring as a condition of coverage

New Toronto Electric can provide the ESA inspection report that your insurer requires.