What do Cu and Al mean in electrical wiring?

What is the UL Al-Cu marking on receptacles?

  • In about 1974 or so UL published a pamphlet on aluminum wiring which warned that the wiring devices with the "Al-Cu" marking should not be used with aluminum wire. In about 1972, UL and the wiring device manufacturers agreed on a test standard for receptacles for use with Aluminum Wire.

Are CO/ALR devices the same as Al-Cu or CU-AL devices?

  • Since devices marked COALR or CO/ALR conform to the UL standard for compatibility with aluminum wire, the devices with CO/ALR markings must be considered differently - they are not the same as the AL-CU or CU-AL devices.

Is it safe to use aluminum wire for electrical wiring?

  • Aluminum wire connections can overheat enough to start a fire without ever drawing enough current to trip a circuit breaker. Making proper repairs to aluminum electrical wiring, using the proper electrical wire connectors and methods, can bring the level of electrical wiring safety in building to about the same as a copper-wired building.

image-What do Cu and Al mean in electrical wiring?
image-What do Cu and Al mean in electrical wiring?
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