Aluminum Wiring in the Home

Aluminum Wiring in the Home

Aluminum is used extensively for electrical transmission throughout British Columbia.  BC Hydro supplies power to our homes using aluminum cable.  It is light weight, strong, inexpensive and a good electrical conductor. Inside our homes the wiring is usually made of copper.  In the mid-1960’s, a large increase in the price of copper resulted in aluminum being used in home wiring rather than copper in many cases.  Aluminum was much less expensive than copper, and readily available.  The use of aluminum in homes continued until the second half of the 1970s.  Today, nearly half a million homes in Canada still contain aluminum wiring.

How do I know if my home has aluminum wiring?

Aluminum wiring is easy to identify by color. Looking at the bare wire in electrical outlets will tell you if you have aluminum wiring.  But even if you see copper wire, you still may have aluminum wire connected to it behind the outlet. You will need to check the main panel or look at the plastic jacket of the wire to see if “aluminum” is printed anywhere on the wire to be sure. If in doubt, your home inspector or an electrician can tell you for certain.  If you also wish to look for yourself, InspectAPedia has a useful page on aluminum wiring, along with a free informative book on the topic for download.

If my home has aluminum wiring, should I be worried?

Aluminum wiring, when installed and maintained properly, is perfectly safe. But you should be concerned enough to ensure that it has been installed correctly.  If you are considering purchasing a home containing aluminum wiring, you should also contact a home insurance agent before purchasing the home. There are some special safety considerations with aluminum wiring:

• Corrosion – aluminum will corrode when it comes in contact with other metals in the presence of moisture.
• Oxidation – aluminum oxidizes readily in air, forming a hard coating of aluminum oxide on the outside of the wire. Aluminum oxide is more resistant to electrical current flow, and may cause some deterioration of connections and increased hazard.
• Malleability – aluminum is softer than copper, and care has to be taken to not over-tighten screws. The aluminum could continue to “flow” after over-tightening, causing the connection to loosen.
• Thermal expansion and contraction – aluminum expands and contracts in response to temperature changes more than copper. This may cause connection to loosen over time.

What can I do about it?

If you have aluminum wiring, contact a qualified electrician to evaluate the safety of the home.  Rewiring the entire home with copper wire is the most effective solution, but is often impractical.  Using copalum crimps to join copper to aluminum is generally considered the next best option.  This, or any other electrical repair work, should be performed by a licensed electrician.

For a detailed discussion of copalum repairs, visit the
Consumer Product Safety Division of the US Government.