During the 1970s, aluminum wiring became very popular and used all over the United States. Since that time, aluminum wiring has been shown to have its flaws. Many house fires and even deaths have been reported to have been caused by hazardous aluminum wiring.
The main problem with aluminum wiring is something called “cold creep”. When aluminum wiring warms up, it expands. When it cools down, it contracts. Unlike copper wiring which is used now in homes, aluminum goes through a number of warm/cool cycles and it loses tightness each time. To make the problem worse, aluminum corrodes when in contact with certain types of metal, so the resistance of the connection goes up. This causes it to heat up and corrode even more. Eventually the wire can start to get very hot, melt the insulation or fixture it’s attached to and possibly even cause a fire.
Aluminum wiring can also be very dangerous because it can take many years to reach a very high temperature while still remaining electrically functional in the circuits.
The most certain corrective action would be to rewire the home with copper wire. This, however, can be expensive and sometimes impractical. A practical alternative to rewiring can be achieved by a method called “pigtailing”. This uses a specially selected connector and installation method to splice a short length of solid copper wire to each aluminum wire end. The copper wire “pigtail” is then connected to the circuit breaker, light fixture, receptacle, dishwasher, or other termination. This method is only effective if the connections between the aluminum wires and the copper “pigtails” are extremely reliable. Other less effective options are to replace certain failure-prone types of devices and connections with ones that are more compatible with aluminum wiring and to remove any ignitable materials from the vicinity of the connections.