Printer friendly version

change text size:

Aluminium wiring only causes wiring problems if the wire oxidises at the connections; learn what to look for and how to make corrections.

Aluminium wiring was extensively used in home building from 1965 to 1976; although it is no longer a popular wiring method for branch circuits, it is often used to bring electricity into the house from the power lines on the street.

Aluminium wiring in your home will operate as safely as any other type of wiring if the proper materials are used and it is installed as per the manufacturer’s instructions and the Ontario Electric Safety Code. It is still permitted under the Ontario Electrical Code to use aluminium wiring for residential interior wiring.

Problems with aluminium wiring occur at the terminations, the ends of the wire. If your home has aluminium wiring and there are problems with it, they will often show as warm cover plates of switches or receptacles, darkening of white receptacles, flickering lights, or the smell of hot plastic insulation. The problems are caused by oxidation of the aluminium, which results in the white coating we have often seen on aluminium things. The oxidised surface is a poor conductor of electricity; it generates heat from its increased resistance, and other problems such as melting of insulation, and thermal creep of the wire at the connection can occur.

If you suspect problems, we recommend that you choose a reputable and qualified electrical contractor experienced in repairing aluminium wiring, although you can do the work yourself if you follow sensible safety precautions (see below).

Ask your electrical contractor to visually check the wire terminations at receptacles and light switches, as well as in the fuse box, looking for signs of melted insulation, discolouration of the wire, or any signs of white oxidation on the wire surface.

If problems are found, the corrections are usually simple, and do not involve re-wiring the house.

If problems are found at switches or receptacles, it is easy to correct them. The Ontario Electrical Safety Authority has issued a Technical Bulletin describing how to do this. Any damaged aluminium conductors are cut back, and joined to a copper tail using a twist-on type of connector approved for use with aluminium. Such connectors are coloured brown or purple (depending on the manufacturer). The copper tail is then terminated at the terminal screws of the switch or receptacle. We add to this the cleaning to bright metal of the end of the aluminium wire and coating it with anti-oxidant grease before making the joint. A small tube of the grease is available at minimal cost from most building supply stores.

If you want to replace the switches or receptacles, after cutting back any damaged aluminium conductors they can be connected to new switches or receptacles marked CO/ALR, which are the only devices currently approved for use with aluminium wiring.

Electrical panel connections should be checked for signs of overheating. Where fuses protect heavy loads, they should be temperature sensitive, type D or P.

1. Never work on a powered electrical system; always remove the fuse or switch off at least the breaker feeding the switch or receptacle you intend to correct. It is safer to switch off the main disconnect or main breakers and de-power the whole house. Remember to let everyone know what you are doing, and put a sticky note by the breaker or fuse you switched off.
2. Never open the mains feed side of any electrical panel, as there is no disconnect to de-power this and you are entirely unprotected.
3. If you are working on the panel, you must de-power it using the main disconnect or main breakers.
4. Before you start working, check that the power is off at the receptacle or switch using an electrical tester.
5. Keep notes about which receptacle or switches you corrected; remember it is better to correct them all rather than just a few problematic ones.
6. Take photographs to document the correction that you did; a future buyer might wish to see these.
7. After the work is completed you can arrange for an inspection by the Electrical Safety Authority, who can issue a Certificate of Inspection for your records and possibly for your insurance company.