There is a lot of hearsay and rules of thumb in respect to electrical wiring requirements. I regularly direct others to reference the actual rule not assume there is one. A question came up about the use of aluminum conductors for branch circuit wiring. Everyone including myself was confident the NEC prohibited it. I found myself guilty of buying into the hearsay on this one. There was no such wiring restriction contained in the National Electrical Code.
There are sections that require copper conductors only. There are also restrictions on aluminum conductors under specific conditions. However, there is no such restriction on their use for branch circuits. In fact, aluminum conductors are listed as suitable for such installations. This is consistent throughout the National Electrical Code.
Everyone is aware of the problems that arose from the use of aluminum conductors many years ago. The danger was mainly associated with terminations and improper installation. New alloys were introduced that have comparable characteristics to copper conductors. Terminals for use with aluminum conductors were also improved. Yet aluminum conductors for 15 and 20 ampere branch circuits seem nonexistent.
Here is what I can find. There are some state and local requirements that restrict such use. The Consumer Safety Products Commission also sees such installations as unsafe and supports only a single method for rectifying existing installations (Shown Below). Many insurance company’s also exclude coverage for properties containing aluminum conductors for branch circuits.
More information will be gathered to reach a definitive conclusion as to why there is the belief that aluminum conductors can’t be used. Especially with today’s copper prices. Aluminum conductors could offer considerable savings.
If you have any additional information regarding aluminum conductors for branch circuit wiring feel free to post comments.