If you own a Calgary home built between roughly 1965 and 1978, this is worth ten minutes of your time. If your home was built after that, you can stop reading — this isn’t your problem.
Why this is a question at all
Copper prices spiked in the mid-1960s. Builders across North America switched to aluminium for branch circuits — the wiring that runs to your outlets, switches and lights — and kept using it for about a decade.
The wire itself carries current perfectly well. What causes trouble is what happens at the ends of it. Aluminium expands and contracts more than copper as it heats and cools, so connections that were tight fifty years ago work loose. It oxidises readily, and unlike copper oxide, aluminium oxide resists current — which builds heat at exactly the point you least want heat.
A loose, oxidised connection inside a wall box is how a wiring issue becomes a fire.
That said: thousands of Calgary homes have run on aluminium branch wiring for decades without incident. This is a “get it looked at properly” situation, not a “leave the house tonight” situation.
How to check, without touching anything dangerous
- Start with the age of the house. If it was built before 1965 or after about 1978, aluminium branch wiring is unlikely. Between those dates, it’s worth checking.
- Look at the panel — with the cover ON. You do not need to open anything. Where cables enter the panel, the outer sheath often has printing on it. You’re looking for the word ALUMINUM or the letters AL. Copper wiring is usually marked CU, or not marked at all.
- Check an unfinished basement or the garage. Exposed cable runs across joists are the easiest place to read markings.
- Look at the colour of the sheath. Aluminium cable of this era was frequently sheathed in a distinctive colour, but this varies enough that it isn’t reliable on its own. Use the printed marking.
What not to do: don’t remove the panel cover, and don’t pull outlets out of walls to look at the wires. There is live equipment behind both, and the check isn’t worth the risk. If you can’t tell from the outside, that’s what an electrician is for.
What it means if you do have it
Three broad options, and the right one depends on the house rather than on a preference.
Do nothing yet, but get it inspected. If the wiring is in sound condition with no evidence of heat at terminations, a documented inspection may be all that’s needed right now — and it gives you something to show an insurer.
Pigtailing. A short copper tail is joined to the aluminium at each device using a connector approved for that purpose, and the copper lands on the outlet or switch. Every device in the house gets the same treatment. Far cheaper than a rewire, and no walls come open.
Full rewire. Every branch circuit replaced with copper. More expensive and more disruptive, and the right answer when insulation is brittle or damaged, when there’s evidence of overheating in the runs themselves, or when walls are open for a renovation anyway.
Anyone who quotes you a full rewire without having looked inside a box is selling, not diagnosing.
→ More detail: Aluminium Wire Replacement & Rewiring
The insurance conversation
This is what catches most people, and it usually catches them at the worst moment.
Many Canadian insurers ask about aluminium branch wiring. Some decline it. Some require an inspection and documented remediation before writing or renewing a policy. Some simply charge more.
If you’re buying a home from this era, ask your broker before you remove conditions. If you already own one and haven’t had the conversation, have it before renewal rather than during a claim.
A permitted, inspected remediation with paperwork is what insurers want to see.
Signs that mean call sooner rather than later
- An outlet, switch or cover plate that is warm to the touch
- Scorch marks or discolouration around a receptacle
- A burning or hot-plastic smell, even faintly, even occasionally
- Flickering that isn’t the bulb
- Outlets that work intermittently
Any of those, stop using the circuit and get it looked at.
→ If it’s happening now: Emergency Electrician
The short version
Check the age of the house. Look for AL or ALUMINUM printed on the cable sheath at the panel or in an unfinished basement. Don’t open anything. If you find it, get an inspection before you decide anything — and talk to your insurer before they talk to you.
Not sure what you’re looking at? Send us a photo, or call (403) 690-3994.