Why is aluminum wiring a problem?

Many people hear the words 'aluminum wiring' and think it is a death sentence, yet others have never heard of it, or why it is a problem. Many homes were wired with aluminum wiring, sometimes all circuits are aluminum, and sometimes only a few, or even one.

Between the years 1965 and 1975 (approximately), aluminum wiring was used, but the manufacturers realized ther was a problem, and the composition of the alumimum wiring changed around 1972 so it wasn't as problematic.

First of all, many utility companies use aluminum from the utility pole to your service connections due to its lighter weight, so it is not illegal. When connections loosen up, the lack of a tight connection is what causes 'arcing' which is kind of like a spark because of this loose connection. When arcing happens in an electrical service box and something like paper insulation catches this spark, you can have a fire.

If wiring connections at the receptacle or wall switch loosen up, this can also cause a fire. These things loosen up because all metals expand and contract at different rates when current passes through it. It gets hot, then cools down. After many years, this heating and cooling happens thousands of times. When aluminum expands and contracts at a different rate than the screw that holds it, this difference in expansion and contraction over the years causes connections to loosen up. Also, loose connections cause more current to gather at this poor connection and wires get hot. Hot wires within walls can cause a fire. Did you ever hear of someone opening up a wall during a renovation and finding old newspaper? This is an easy way for a fire to occur.

Wire can also 'work harden'. This is when you bend and flex wiring and other metals. When you bend some metals, the point at which they bend tends to harden, and if you keep on flexing it, it eventually breaks. So imagine running a wire behind a wall where it has to bend and flex in order to be 'snaked' within walls. If you were to look at this bend location closely, you would see minute cracks. Work hardening can also cause wires to fail.

Pigtailing was the main way to alleviate aluminum wiring problems, but many electricians in my area no longer do this. They recommend the wiring be replaced. So, it is their call - follow their advice. - Ray