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Aluminum wiring a good idea for 240v circuits above 40a?

BrunoF | Posted in General Questions on

I know that it is allowed by code but is it a good good idea to use aluminum wiring in the house for the larger circuits above 40a like the range and heat pumps?

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  1. dalee | | #1

    When I saw the price of copper wiring I had the same question. I decided to trust the electrical code authors over the collection of options expressed online.

    I take a lot of care on the terminations. I always use a torque screwdriver.

  2. Expert Member
    BILL WICHERS | | #2

    Aluminum prices have gone up a lot too, so the savings over copper isn’t as much as it once was.

    My recommendation would be to never consider aluminum for anything 8 gauge (40 amps with copper and NMB cable) and under (10, 12, etc). There isn’t much savings there, so I don’t see any real reason to go with aluminum.

    For services, you’re in the “ought” range, 2/0, 4/0, etc. I don’t have a problem using aluminum wire there, but I do recommend using no-ox paste on the connections for some extra insurance — and use it right, working it between the strands of the conductor and not just smearing it on the outer layer. Chances are your electric utility will be bringing in aluminum to the meter regardless.

    For anything in between, it’s a bit of a judgement call. Aluminum is fine when installed correctly in the larger sizes, but the cost savings for an entire job including all materials and labor is often not all that much for residential scale projects. I use copper for everything in my own home, including between the meter and main panel, where I used copper because it’s a little smaller for the same ampacity, making it a bit easier to install.

    On commercial projects, I always spec compression lugs (big crimp terminals) for aluminum wire, and I only use aluminum for very large circuits of over 600 amps where there is more of a cost savings. Code is fine either way as long as you follow the ampacity tables for the wire and application.


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