Was your house built, in the late 60's or early 70's, if so your wiring is probably Aluminum. Aluminum was and still is approved in the National Electrical Code NEC and Underwriters Laboratories UL rated. However, there can be safety hazards in a home wired in aluminum especially in older homes. Many homes wired over 30 years ago with aluminum pose a multitude of fire and safety issues that most homeowners may not be aware of.
The problem with the 1350 series aluminum alloy used in the 60's and 70's was that the aluminum wire was designed for power transmission and not for branch circuitry. A straight run of 1350 Aluminum alloy wire did not pose the safety hazard. However, when homes were being wired with aluminum on a branch circuitry every connection made to a junction box, outlet, and switch, posed a safety and fire risk, and many homes wired in the 60's and 70's today still have the original aluminum wiring.
Aluminum is a softer metal and it expands and contracts at different rates then the other metals such as copper used in wiring. The electric current will change the temperature of the wire, causing joints to loosen and compromise the connection.
Once the connection is compromised there is further temperature gains that can give to arching or igniting a fire.
Most metals when exposed to the atmosphere oxidize. Copper when oxidized forms a conductor, on the other hand with aluminum oxide, it forms resistance which at a connection will cause an extra build up of heat. The oxidation builds up over time and will affect the electrical distribution.
What to look for and what can be done if your aluminum wiring is a probable safety and fire hazard.
- Junction boxes, outlets, and switches should be rated for aluminum connection, and stamped with AL CU or CO ALR, if not they should be replaced with the aluminum rated fixtures.
- Aluminum wire should not be connected with push-in terminals, which is an extremely dangerous connection.
- Every connection should be checked for any sign of melting, burnt or darkened areas.
- Lights flickering, warm to the touch receptacles, and any noticeable odor such as, the smell of burning plastic should be inspected by a licensed electrician.
Industry wide, opinions on the methods to replace or repair aluminum wiring are debatable, other than the complete rewiring with copper wire which can be very expensive. A second option is the Copalum crimp repair.
The Copalum crimp repair is the next best solution to rewiring with copper, although it is not a readily available solution because, the crimping tool can only be leased by licensed electricians thoroughly trained and certified by the manufacturer, in the Copalum procedure.
Finally, electricians often use pig-tailing using special twist connectors that are compatible with connecting aluminum and copper, as the materials to repair with this method are readily available. A licensed electrician with specific experience with this repair should only use this method.
Although the aluminum available and used today is much safer then 30 years ago, AA-8000 series, UL rated and NEC approved, most electricians would not run aluminum in any new residential home.