Aluminum wiring is sometimes found in older houses, and people often become anxious about connecting it with copper wiring in extensions, unsure of whether it is safe or efficient to do so. They are actually correct to be worried about this, as the uniting of the two metals can cause a chemical reaction called electrolysis, which may lead to corrosion of the copper wiring, which ultimately is a fire risk. However, there are a couple of ways in which aluminum and copper wiring can be safely joined together.
Combining Copper and Aluminum Wiring
It is possible to connect the two different types of wires safely if you do it via a system called CU/AL. These often appear as little box-shaped fittings, and they are intended to keep the wires from connecting and corroding each other. Before using this method, the aluminum items should be wrapped in an anti-oxidizing gum or paste. Until recently, 3M made a nut connector that combined the two, but this has recently been connected to fire hazards and may no longer be available. Check your local hardware store or online retailer to see what alternatives, if any are on the market and what products have the highest safety ratings.
Another answer is to ask an electrician to pig-tail your aluminum, which is a method that will allow you to avoid having to connect the two. This is similar to the CU/AL connections, but it can be carefully done with a machine that crimps the aluminum with several tons of force. This may be a costly project, but the extra expense on a professional electrician will ensure that you are safe when you use electrical equipment in your home.