According to Electrical Safety Authority (May 1, 2009 Supersedes FLASH 06-03-FL Aluminum wiring in residential installations)
“Issues with aluminum wiring”
Since January of 2003 the Electrical Safety Authority has received an increasing number of questions about the safety of aluminum wiring. In particular, purchasers or owners of homes built from the mid 1960’s until the late 1970’s with aluminum wiring are finding that many insurers will not provide or renew insurance coverage on such properties unless the wiring is inspected and repaired or replaced as necessary and this work is inspected by ESA and a copy of the certificate of inspection is provided to the insurer. In some cases the insurer may require replacement of the aluminum wiring with copper wiring.
heck with your insurance company for their requirements. Some homes may have a mixture of aluminum and copper wiring. Reported problems with aluminum wiring have been related to the overheating and failure of aluminum wiring terminations. This is due to aluminums tendency to oxidize and its incompatibility with devices designed for use with copper wiring. Warm cover plates or discolouration of switches or receptacles, flickering lights, or the smell of hot plastic insulation may evidence these problems. Each home will be different and must be assessed on its own. It is highly recommended the homeowner hire a licensed electrical contractor who is knowledgeable in the special techniques required for working with and repairing aluminum wiring. The contractor should do an assessment, make the necessary repairs, and have the work inspected by ESA. The homeowner should obtain a copy of the Certificate of Inspection for their records and for their insurance company (if requested).
As mentioned above, where problems exist with aluminum wiring they are usually found at termination points. This necessitates the opening of all outlets (receptacles, switches, fixtures, appliance connections, and in the panelboard) and visually inspecting terminations for signs of failure and overheating without removing or disturbing the devices or wiring. There should be no signs of overheating such as darkened or discoloured connections, melted insulation, etc.
Where problems are found the damaged aluminum conductor should be cut back to remove the damaged portion and then the necessary repairs made”