Yes, aluminum wire is safe if installed correctly. Aluminum wire was used extensively at one time and is still used for large feeders for its lower cost compared with copper wire. In older homes you may find that lighting circuits use aluminum wire. Whenever aluminum wire is used, extra care must be taken not to nick the wire or bend it repeatedly when splicing or connecting to outlets. All wire connectors, terminations and devices must be approved for use with aluminum wire. Look for markings like “CU/AL”, “CU-AL” or “CO/ALR” on any devices or connectors to be used with aluminum wires. Beware markings like “Cu Only” or a Symbol for “No Al”. An anti-oxidant must be applied to all splices or terminations as per the instructions on the anti-oxidant product.

You can see that the connections in this photo were not done properly. Heat damage is obvious in the neutral splice ... that's the one where the wires are supposed to be white! If your home or business contains aluminum wiring, be alert for any signs of excessive heat at switches or receptacles or any other signs that might indicate trouble in the wiring. If in doubt, have it checked!

Copper wire will stand up to handling better than aluminum, and is less prone to problems resulting from oxidation or cold-flow. Wherever practical it is a good idea to replace aluminum wire with copper. Use of copper wire is the only way to go for any new wiring other than large feeds such as a service feeder.

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