I have a electrical project to do, and could save about $300.00 by using aluminum wire since I can get it free, but I have never used aluminum before, and am not sure if it is a good way to go.Aluminum wire is relatively safe on it\'s own. But care must be taken not to join aluminum wire to copper, or to any appliance, or device that is designed only to be connected with copper wire. When you combine aluminum and copper extra heat is produced at the point of connection, and a fire can result. In the 1970\'s aluminum was being used a lot, but the technology was new, and a lot of stupid mistakes were made. I had a friend who had a fire start in his home because the house was wired with aluminum wire, and an electric baseboard heater that was only designed for copper was installed. You might save a few bucks in wire, but you should know that aluminum wire is less conductive, and it can have a negative effect on your electricity bill in the long run. But you asked if it is safe, and my answer is, for the unskilled on this subject, aluminum wire is absolutely NOT SAFE!Every supply drop I have ever installed larger than 2/0 is aluminum. It is very common and a whole lot cheaper than copper. If you upsize the diameter correctly for your load, you will have no more voltage drop/heating than the smaller (yet more expensive) copper over the same distance. Some jurisdictions prohibit copper in branch wiring, or require an additional inspection fee, since every device must be examined for safety.Aluminum wire can be connected to copper wire with the proper connectorI would not recommend it. Aluminum wire expands and contracts a great deal causing the connections to become loose, or break. That is what I was taught.Other related question