Homes traditionally have been built using copper wiring.  However, in the 1960s and 1970s, as copper prices soared, homebuilders began using much less expensive aluminum wiring.  But aluminum wiring that is not properly installed can be risky.  In fact, the Consumer Product Safety Commission believes homes wired with aluminum wiring are 55 times more likely to have fire hazard conditions than homes wired with copper.  For that reason, many communities in Chicago’s North Shore ban the use of aluminum wiring in new construction.  And many insurance companies refused and still refuse to insure homes with aluminum wiring. 

This article addresses the reasons aluminum wiring causes a problem and some signs you can look for to determine if you have aluminum wiring.  Next month we will address possible solutions.

First, there are three reasons aluminum wiring poses a greater danger than copper wiring:

  1. Softness. Aluminum is much softer than copper.  This makes it easier to damage during installation.  Damaged wire then can cause overheating and, ultimately, fires.
  2. Creeping.  Electricity causes wiring to heat up and expand.  Constant expansion and then contraction as the wiring cools causes the wire to creep out of the terminals holding it in place, resulting in loose connections and overheating. Since aluminum expands at a faster rate than copper, the likelihood of problems is greater.
  3. Rusting.  When metals rust, they form an oxide on the surface.  The oxide that forms when copper rusts can conduct electricity.  However, the oxide that forms when aluminum rusts doesn’t.  This interferes with the flow of electricity, and can cause overheating.

One way to tell if your house has aluminum wiring is simply to check and see if the wiring says Aluminum, or an abbreviation such as Alum or Al.  If you see that, you know your house has aluminum wiring.  But if you cannot tell, there are some other symptoms that may suggest you have aluminum wiring.  These include: