Safety
Aluminum wiring in Ontario homes: insurance, pigtailing and your options
Aluminum branch wiring is one of the two wiring types Ontario insurers ask about most. It isn't illegal and it isn't automatically dangerous, but it does need the right connections. Here's what to know before you call your insurer or an electrician.
What aluminum wiring is, and which homes have it
Aluminum branch wiring means the circuits that run from the panel to your outlets, switches and lights are aluminum instead of copper. It was installed in a share of Ontario homes built from roughly the mid-1960s to the late 1970s, when copper prices were high.
It turns up in detached houses, townhouses and some apartment buildings from that period. In the GTA that points to many subdivisions of the era in North York, Scarborough, Etobicoke, Mississauga, Brampton and York Region. Plenty of houses built in those years used copper, though, so the build date only tells you to check.
Don't confuse it with the large aluminum cable that often feeds a panel or a range. Service and feeder conductors in aluminum are common and still installed today. The concern is the smaller branch circuits.
Is aluminum wiring illegal in Ontario?
No. Aluminum branch wiring is permitted, and there's no rule that you must remove it. The Electrical Safety Authority's position is that it can be safe when it's installed with the right devices and maintained properly. You can read ESA's homeowner guidance at esasafe.com.
The catch is the word "properly". Many homes with aluminum wiring have had outlets, switches and fixtures changed over the decades, often with parts made only for copper. Those swaps are where the problems usually start.
Why the connections are the weak point
Aluminum behaves differently from copper in three ways that matter at a screw terminal or a splice:
- It expands and contracts more as it heats and cools, which can loosen a connection over many cycles.
- It forms a surface oxide that resists current, so a poor contact gets worse over time.
- It is softer, so it can deform under a terminal screw that was tightened for copper.
A loose, high-resistance connection makes heat. Most of the time the result is a warm plate, a flickering light or an outlet that stops working. Left alone, it can damage the device and the box around it. That's why every sensible fix concentrates on the connections.
How to tell if your house has it
You can often find out without opening anything. Stay out of the panel and leave the cover plates on. Look at what's already exposed:
Printing on the cable
Branch cable in an unfinished basement or near the panel is often marked AL or ALUMINUM on its outer jacket.
Silver-coloured conductors
Where wire ends are visible, aluminum looks silver-grey rather than copper-coloured.
The age of the house
A build date from the mid-1960s to the late 1970s is a reason to check, not proof.
Past reports
A home inspection or an insurance form may already mention it.
Finished basements hide most of the evidence. A licensed electrician's inspection confirms the wiring type and, more importantly, the state of the connections.
What insurers ask for
Insurers in Ontario often ask about aluminum wiring when you buy a home, change companies or renew. What they want next varies a great deal from one company to another:
- Some only want to know it's there.
- Some ask for an inspection or a letter from a licensed electrical contractor.
- Some want proof that the connections have been repaired with approved parts.
- A few want the aluminum circuits replaced, or won't offer coverage until they are.
Ask your insurer exactly what they need, in writing, before any work starts. Then the inspection and any repair can produce the paperwork they'll accept the first time. Work done under an ESA permit ends with a Certificate of Acceptance, which is often part of that paperwork.
Your options: pigtailing, rated devices or rewiring
Once an inspection has confirmed aluminum wiring and checked its condition, there are three main ways to deal with it, often combined.
| Option | How it works | Trade-offs |
|---|---|---|
| Pigtailing | Each aluminum conductor is joined to a short copper wire using a connector approved for aluminum-to-copper. The copper end goes to the device. | Leaves the wiring in the walls. Every connection in the house has to be done for it to be complete. |
| Aluminum-rated devices | Outlets and switches marked CO/ALR, designed for aluminum, replace copper-only devices. | Useful for some devices. Not available for every kind of fixture or connection. |
| Rewiring in copper | New copper circuits replace the aluminum ones. | The most complete answer and the most disruptive. Easiest when walls are open for a renovation. |
One thing isn't an option: ordinary wire nuts or copper-only outlets on aluminum wire. They're the source of many of the problems in the first place.
Can you pigtail aluminum wiring yourself?
Ontario lets homeowners do some electrical work in a house they own and live in, with their own ESA permit. Aluminum repair is a poor place to start. The connectors have to be the right type and installed exactly as their maker specifies, every device in the house has to be reached, and a damaged conductor has to be recognized and dealt with.
Anyone you pay for electrical work must hold an ECRA/ESA licence. You can confirm a contractor's licence on ESA's website before you hire.
Buying or selling a 1960s or 70s home
If a buyer's home inspector mentions aluminum wiring, it shouldn't end the deal, but it should start a conversation. Find out how many circuits are involved, whether the connections have already been repaired, and what the buyer's insurer will need.
Sellers can get ahead of it. An inspection before listing, and the repair if it's needed, gives buyers and their insurers clear answers. Keep the ESA certificate and any written report with the house documents.
In North York, the Parkwoods and Bayview Village pages describe homes from this era, and our guide to old wiring in North York homes covers the other wiring types insurers ask about.
How we handle aluminum wiring
Insurers and homeowners both call us about aluminum wiring. We start with a full home electrical inspection to confirm where it is and check the connections, and anything running hot is made safe first. Then we repair every connection or replace the circuits with copper, built to code and inspected by ESA wherever a permit applies.
See aluminum wiring repair and replacement for how the work runs and what affects the price.
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