Aluminum Wiring
Aluminum wiring was used in some homes from the mid 1960's to the early 1970's. During this time period copper was at a all time high. Copper was being used for military purposes and the construction industry needed to find an alternative material to use for residential wiring. Aluminum had been approved by Underwriters Laboratories in 1945 for interior wiring purposes. Aluminum was softer than copper, it could not withstand as much stress when being pulled through wiring chases, it was easily broken if it was damaged or bent and it needed to be at least one wire gauge larger than the equivalent copper gauge. It was cheaper and more available than copper so it was used to wire many homes during this era. As long as it was installed correctly it was deemed safe to use. However, little emphasis was put on the expansion and contraction of the aluminum wire. This led to arcing at the connections. Also during this time, code enforcement was scarce which allowed many installation errors to go unnoticed.
Aluminum wiring was used and still is used for wiring large appliances (such as furnaces, dryers and electric ranges) and as feeders to panels. Aluminum wiring is not the problem. The connection to the device is the problem. Most switches and receptacles that were used were not compatible with aluminum. Aluminum has to be terminated with crimp sleeves, screw terminals or lugs and has to be treated with an oxide inhibitor that is suitable for aluminum. The devices had screws and terminals that were rated for expansion and contraction of copper and they caused the aluminum wire to become loose and oxidize. When an electrical connection is loose it causes the current to arc. Arcing leads to fires.
There are many homes in the area that have aluminum wiring. The life expectancy of aluminum wiring is around 30 years. Some insurance companies charge higher premiums for homes containing small branch aluminum wiring provided that you take the proper steps to make it safe. Some will refuse to insure your home period!
There are a few ways to make the system safer. "Pig tailing" all of the devices which involves adding a small section of copper wire to the device and using a special (expensive!) wire nut to join the copper and aluminum. You can also change out all of the devices with ones that are approved for use with aluminum. The best way to ensure the safety of your home (and the most expensive) is to rewire it. Since the life expectancy of the aluminum wiring is over, many insurance companies are pushing for a rewire.
During a home inspection aluminum wiring is noted on the report if it is found. A licensed electrical contractor should be consulted to evaluate the electrical system to see if it is safe.
Aluminum wiring was used and still is used for wiring large appliances (such as furnaces, dryers and electric ranges) and as feeders to panels. Aluminum wiring is not the problem. The connection to the device is the problem. Most switches and receptacles that were used were not compatible with aluminum. Aluminum has to be terminated with crimp sleeves, screw terminals or lugs and has to be treated with an oxide inhibitor that is suitable for aluminum. The devices had screws and terminals that were rated for expansion and contraction of copper and they caused the aluminum wire to become loose and oxidize. When an electrical connection is loose it causes the current to arc. Arcing leads to fires.
There are many homes in the area that have aluminum wiring. The life expectancy of aluminum wiring is around 30 years. Some insurance companies charge higher premiums for homes containing small branch aluminum wiring provided that you take the proper steps to make it safe. Some will refuse to insure your home period!
There are a few ways to make the system safer. "Pig tailing" all of the devices which involves adding a small section of copper wire to the device and using a special (expensive!) wire nut to join the copper and aluminum. You can also change out all of the devices with ones that are approved for use with aluminum. The best way to ensure the safety of your home (and the most expensive) is to rewire it. Since the life expectancy of the aluminum wiring is over, many insurance companies are pushing for a rewire.
During a home inspection aluminum wiring is noted on the report if it is found. A licensed electrical contractor should be consulted to evaluate the electrical system to see if it is safe.