Identifying Aluminum Wiring
Aluminum Wiring
Without opening any electrical panels or other devices, an inspector can look at printed or embossed letters on the plastic wire jacket where wiring is visible in the attic or at the electric panel. Some aluminum wire has the word "Aluminum" or a specific brand name such as "Kaiser Aluminum" plainly marked on the plastic wire jacket. The photo on this webpage shows a dark colored wire jacket with green print indicating "Kaiser Aluminum." Some white colored plastic wire jackets are inked in red; others have embossed letters without ink and are hard to read. Try shining a light along the wire.
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Aluminum wire is found in dwellings built between 1965 to 1973. In 1972, manufacturers modified both aluminum wire switches and outlets to improve the performance of aluminum-wired connections. The switches and outlets are labeled "CO/ALR". CO indicates that the device is acceptable for copper wire, and ALR means it is acceptable for aluminum wire.
Aluminum wire does not behave the same as copper wire because aluminum wire has approximately a 30 percent higher expansion/contraction rate than copper. When aluminum is exposed to the atmoshpere, a film of aluminum oxide forms on the metal surface. The oxide is an insulator, not a conductor of electricity. The oxide becomes a problem as it continues to build up on the wire, it builds up resistance. Heat comes with the resistance, thereby reducing the voltage.
To prevent oxidation at the connections of aluminum wires to other wires or terminal screws, it is recommended that a good anti-oxidant compound such as Alnox or Penetrox is applied at the point of connection.
Aluminum wire does not behave the same as copper wire because aluminum wire has approximately a 30 percent higher expansion/contraction rate than copper. When aluminum is exposed to the atmoshpere, a film of aluminum oxide forms on the metal surface. The oxide is an insulator, not a conductor of electricity. The oxide becomes a problem as it continues to build up on the wire, it builds up resistance. Heat comes with the resistance, thereby reducing the voltage.
To prevent oxidation at the connections of aluminum wires to other wires or terminal screws, it is recommended that a good anti-oxidant compound such as Alnox or Penetrox is applied at the point of connection.
Identifying Aluminum Wiring
SUPERIOR Real Estate Inspection Services Derrick Walls, Owner/Professional Inspector License #8276