Aluminum Branch Circuit

Is aluminum wiring for a branch circuit acceptable in any cases, such as a 60-amp circuit feeding out of the main panel to a sub-panel or an RV hookup?

Solid aluminum or stranded aluminum?

I know the answer but want to walk through this.

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Very typical if stranded

Thanks. It’s stranded wire. Looks like it’s original to the 45-year–old house. I know I would never use aluminum.

Why not?

What type of metal were the service conductors?

Aluminum is OK as long as it’s maintained. Connections deteriorate faster than copper.

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But, who actually “maintains their wiring”? Most people are too lazy or too busy (or scared shockless of electricity) to even change their A/C filter; or too frugal to pay someone else to do it.

Cables from generating stations and virtually all outside wire is aluminium.
Nothing wrong with it.


Be sure and use anti oxidant where appropriate. The following clipped from a google search.

Code for Aluminum Wire Paste

Rule 12-118(1) states that adequate precaution shall be given to the termination and splicing of aluminum conductors, including the removal of insulation, the cleaning of the bared conductor, the compatibility and installation of fittings.
Aluminum conductors are more malleable than copper, and care is needed to not cut or nick during termination. Nicks or cuts at terminations result in a vulnerable spot that may end in breakage of the conductor or a hot spot.

Rule 12-118(2) requires that a joint compound get used with stranded aluminum conductor connections, but does not need it for solid aluminum conductors. Even though not required by code, bare ends of solid aluminum conductors should get coated with the approved joint compound. Note: The compound is conductive and should get used sparingly. Any excess compound should get removed.

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What is the source of this information?

People who don’t want their house to burn down or don’t want problems resulting from the inspection.

Some homeowners don’t know how to reset a breaker.

That’s why in our reports we recommend aluminium wiring be evaluated/serviced by a qualified electrical contractor unless the seller can produce documentation showing that it has been recently done.

IMO the problems with aluminum conductors originate with the installer. If they’re installed correctly there is nothing to maintain and they should perform similar to copper conductors.

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Robert, what’s the most common mistake installers make?

The two that I see often are one, the conductor is not stripped properly and two, the terminal is not torqued properly. Aluminum conductors should not be stripped by cut a ring around it with your knife as you would do with copper conductors. That ring can damage the aluminum strands and they may weaken or break when tightening the terminal. Aluminum conductors should be stripped like you were sharpening a pencil with a knife.

Improper torquing is something that causes the most failures with both aluminum and copper conductor terminations. Although not required with anti-oxidant paste is cheap insurance to ensure that the termination will last for lifespan of the equipment.