Things you should know about aluminum wiring in houses.
First off, aluminum wiring can be safe if properly utilized. From high voltage transmission lines to the service entrance conductors feeding your home, these conductors are usually aluminum.
So what’s the big problem with aluminum wiring?
When used as smaller conductors such as awg#10 for a 20amp circuit or awg#12 for a 15amp circuit in a home, these conductors can be hazardous if not installed correctly.
Aluminum is not as conductive as say copper or gold or silver, because it has a higher resistance and because of its properties. Aluminum expands and contracts under loads significantly more than copper. As the “load” or amperage increases on the conductor, it expands. When the load decreases, the conductor contracts back to its original size. This constant expansion and contraction, combined with oxidation, cause the terminations in wire connectors and on devices such as outlets and switches to become loose. When loose, they will arc and arcing will eventually lead to a fire.
That is why small aluminum conductors make a poor substitute for copper.
For larger appliances and large “feeders” this does not pose a big problem.
The connection methods for the larger wires take this expansion and contraction into account. Additionally, anti-oxidant compounds are required on these connections.