Aluminum branch wiring was used during the 1960s and 1970s in many homes for the wiring of receptacles, switches and other devices. Aluminum does not conduct electricity as efficiently as copper and creates more resistance and heat.
Single strand branch aluminum wiring has been implicated in a number of house fires. The cause of these fires is not normally the aluminum wire itself rather they are the result of improper connections.
Aluminum wiring also expands and contracts more than copper, thus there is a tendency for the connections to become loose at the devices (switches, outlets and breakers) and junction boxes. Oxidation will build up between the loose connections, causing an increase in the amount of heat generated, which can then pose a potential fire hazard.
Do not replace devices with “copper only rated” devices because they also could be a fire hazard. There are copper/aluminum rated devices available but they’re much more expensive than the standard copper only rated devices.
In the interest of safety, when it comes to aluminum wire, you need to contact a licensed electrician if:
Outlets and switch cover plates are unusually warm or warped
Smoke or sparks are coming from receptacles and switches
There are strange odors in the area of receptacles and switches
You have untraceable problems with plug-in lights and appliances
Lights periodically flicker.
Many individuals and insurance companies believe aluminum wiring should be removed and replaced with copper. It should be mentioned that this is not always necessary because there are approved or recognized methods for making these systems safe.