Why are copper connectors not generally compatible with aluminum wire?
Copper has a lower rate of thermal expansion than aluminum has, and consequently, soft aluminum wire tends to over compress itself (creep) by virtue of its own expansion when captured in a slower expanding copper connector . This often leads to a loose joint, oxidation and a breakdown of conductivity. By contrast the aluminum connector expands at the same rate as the captured aluminum wire and the contact pressure remains constant and tight.
