Based on a previous question regarding wiring a hot tube, I've decided to run #2 THHN Aluminum from my Square D main panel to the hot tub sub-panel, this would give me the ability to expand in the future if I wanted to do so. I plan to have a 90 amp breaker in the main. After giving it some thought, I have only one concern. Will #2 wire fit onto a 90 amp breaker?

  • It would have to. Breakers must accept the required wires for their ampacity, plus a couple of extra sizes for voltage drop's sake. AL wires are required, according to their large institutional customers e.g. builders. Dec 2 '21 at 22:42

According to the brochure for the Square D QO 90 Amp Breaker it can handle 4 AWG to 2/0 AWG, so yes. And thanks to NoSparksPlease, Homeline too.

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    And in the event that you are running a wire size (for voltage drop reasons) that is bigger than the breaker will take, you "just" (at these wire sizes the air quotes are needed) pigtail the largest wire your breaker takes and join that to the yet larger wire with an appropriate Polaris connector or similar.
    – Ecnerwal
    Dec 2 '21 at 16:00
  • Just go to the home store, ask for some help to grab a 90 amp breaker and get the guy to cut an inch or two of the wire you are planning to use. Then strip it and see if it fits. And again, I'll say, don't forget the "goop" on AL wires (Noalox) on ALL connections. It's really important, if you don't, the AL will oxidize over time and the connection will either fail or become a fire hazard or both. Dec 2 '21 at 16:43
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    No! "Does it fit" is not valid. Enough effort and you can often make something fit that shouldn't. On the flip side, that logic would allow smaller wires (which are not safe!) as long as they aren't too loose. You must check the specs. Which should be clear on the package or included instructions. So "go to the home store" is correct, but not "try and see". Dec 2 '21 at 16:46
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    Yes for Homeline too rexel-cdn.com/products/… Dec 2 '21 at 16:59
  • Thanks All, appreciate the help.
    – missin44
    Dec 2 '21 at 23:20

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