More than 2 million homes were built or remodeled in the United States during the 19960s and 1970s using aluminum electrical wiring. If you currently own one of those home, your most valuable possession is at risk. Every light fixture, every receptacle outlet, every switch, every spliced connection is a potential fire looking for a place to happen. The typical home has well over 200 connections so there are many potential danger spots where fires can start. You’re probably asking the question, why was aluminum wiring used if it’s so dangerous. Good question.
Aluminum wire was used for several reasons. First, the cost of copper started to rise sharply around the mid-sixties so homebuilders started using aluminum wiring to keep the cost of new homes down. Second, electrical contractors started using aluminum wire during the same period when doing remodels and repairs to keep their cost down. Third, it was used in the process of manufacturing mobile homes to keep their weight as well as their cost down. No one knew the dangers that aluminum wire presented because it was a danger that would only become apparent with the passing of time. No one knew that they were building homes with a firebomb waiting to explode ten, twenty, thirty years later.
There really isn’t any problem with the aluminum wiring inside the walls of homes, the problem is inside the device boxes and splice boxes where the wire connects to receptacles, switches, light fixtures, or to other conductors. It’s a metallurgical problem because aluminum expands and contracts at a much greater rate than copper wire and that movement cause the connections to work loose. As the connections become loose, a high resistance to the passage of electric current develops. This opposition to the free flow of electric current causes the connections to heat up. In many cases, enough heat is generated to set the surrounding structural material on fire.
Another danger of electrical connection made with AL (Aluminum) conductors arises from aluminum oxide buildup, which adds to high resistant connections. This oxide is caused by the electrolytic action that takes place when two dissimilar metals come into contact. In this case, that happened when AL wires were spliced to the copper wire pigtails on light fixtures and when they were connected to the brass screws on light switches and receptacles. Besides causing a high resistance to the flow of electric current, oxide buildup also causes the wire to become brittle and the wires may break when the switch or receptacle is pulled from the device box. Because aluminum wiring can become brittle and because it can break easily when moved, correcting these problems may not be a project you want to undertake yourself unless your comfortable with the idea that you may have to completely rewire one or more branch circuits.
How do you know if your home is wired with aluminum wiring and not copper? As a rule, this condition is discovered during the routine home inspection conducted before purchasing the home. Another sign that you may have a problem is that receptacle covers and switch plate become warm to the touch. Switches and receptacle are designed to pass electric current through without consuming any power themselves therefore they shouldn’t become warm to the touch.
Currently there are two approaches to solving these problems. The first way is the most expensive and that’s to completely rewire your home using copper conductors. The second approach is to use a special crimp on connector that allows you to safely connect a short copper pigtail to the aluminum conductor. AMP Corporation makes a crimp on connector called the COPALUM connector that effectively isolates the aluminum conductor from the copper conductor preventing the electrolytic action that leads to the generation of aluminum oxide. The COPALUM crimp on connectors is used in conjunction with heat shrink tubing to make a safe well-insulated connection. A good grade plastic electrical tape can be substituted for the heat shrink tubing but the latter makes for a much neater, professional appearing connection.
