Aluminum Wiring
If your house was built in the late 1960s or early 1970s, your electrical system most likely uses single-strand aluminum wiring. At the time, this material was far less expensive than copper. While evidence from the time indicated that this material was safe to use, it was later discovered that the substance was a fire hazard. According to the Consumer Product Safety Commission, homes with aluminum wiring are up to 55 times more likely to catch fire.
Inspect your electrical panel and the cables in your attic or basement for aluminum wiring. If the wiring is made of aluminum, it will have the letters aluminum, Al, or alum stamped on it. If you discover aluminum wiring, contact an electrician who can assess the situation and advise you on your options.