Although aluminum has its advantages since it is cheaper and easier to work with, it comes with the risk of causing house fires because it is a soft metal with a much lower melting point. In other words, aluminum wiring is much more prone to over-heating than copper wire. When the wire overheats, it will not trip a fuse or a circuit breaker, since that is triggered by an excess current, however, it may generate enough heat to spark an electrical fire.
Aluminum wire was used heavily in the 1960s and 1970s and many believe it to be safe because it has not posed a problem since then. However, the longer aluminum wiring is in use, the more it deteriorates and the greater the risk of overheating becomes.
We at Mister Sparky prefer not to take any chances, so we opt for copper in our wiring services.