How Safe is Aluminum Wiring?
Aluminum electrical wiring was installed in some homes and multi-family dwellings as early as the mid 1960s, but mostly during the 1970s.
Aluminum wiring is considered to be less safe than copper wiring under some circumstances. The problem is not so much with the aluminum but with the connections. Aluminum wiring acts as a partial electrical insulator. This can result in higher temperatures at connections (depending on the amount of power used). Aluminum will also expand and contract more than copper wire with the same temperature change. This can increase the stress at connection points. Aluminum is also more brittle than copper and can develop micro cracks at the surfaces. These attributes can increase the chances of a fire.
Due to safety concerns, in 1977, the Government of Ontario established a Commission of Inquiry on the use of aluminum wiring in the home. Following a thorough investigation, over a period of 18 months, the Commission recommended that aluminum wiring should continue to be authorized for residential use.
Do You Have Aluminum Wiring in Your Home?
According to the British Columbia Safety Authority, it is estimated that there are over 450,000 homes in Canada that are wired with aluminum wiring. Check your wiring by looking between open floor joists, in the basement or attic or at the service panel. If the wiring is aluminum and was manufactured before 1977, the outer covering of the cable will be marked, at least every 12 inches, with the word ALUMINUM, or an abbreviation, ALUM, or AL. If the cable was manufactured after May 1977, the marking may be either ALUMINUM ACM, ALUM ACM, or AL ACM.
You may find that a mixture of aluminum and copper wiring is installed in your home. If your home has aluminum wiring and you need to replace a switch or wall receptacle, the replacement device recommended to install has been of a type that is specifically approved for use with aluminum wiring. Devices approved for the use bear the marking “CO/ALR” and CSA. This means “Copper Aluminum Revised” to differentiate these devices from earlier models. The CO/ALR marking identifies the equipment as having been tested and found suitable for use with aluminum or copper wiring by the Canadian Standards Association (CSA). Updating is typically required at all outlet receptacles and switches.
“Pigtailing” is a term used to connect copper tails at working connections. Typical locations for pigtailing would be at light fixtures, major appliance receptacles and GFCI receptacles for example. In order to connect copper pigtails to aluminum, special connectors are used along with a special paste to stop a chemical reaction. Ask your electrical contractor what he recommends for upgrading at all working connections.
Signs of Possible Concern
If you notice any of the following conditions in your home, the causes should be investigated:
• warm faceplates on switches or receptacles;
• strange or distinctive odours in the vicinity of receptacles or switches;
• persistent but intermittent flickering of lights that can’t be traced to appliance or other
• unusual static on radio or television.
Because of the specialized knowledge and techniques required for working with aluminum wiring, it is recommended that any retro-fitting be done by a qualified electrician. If you are considering purchasing a home, make sure that inspection for aluminum wiring is a part of the process. Aluminum wiring need not be of undue concern as long as you have it properly inspected.
Also read: Hiring a Home Inspector, Aluminum Wiring in Your Home, Checking for Molds in Your Home, Leaky Condos, Home Inspection Companies in Victoria BC, What to Do With a Wet Basement, Victoria Home Inspection