#12 gauge w/ 20 amp breaker for 4 ton mini split correct?

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electrofelon said:
Pretty much anything other than NM and UF. So conduit and THHN, MC cable, SE cable would be the most common.
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Just learning here what are the properties of THHN and MC that can handle it at #10 over #8NMB? Is metal clad not NMB with just a metal enclosure?
 
mystycs said:
Just learning here what are the properties of THHN and MC that can handle it at #10 over #8NMB? Is metal clad not NMB with just a metal enclosure?
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It is simply a listing requirement in the product standard for NM and a rule in the NEC.
 
mystycs said:
Just learning here what are the properties of THHN and MC that can handle it at #10 over #8NMB? Is metal clad not NMB with just a metal enclosure?
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MC cable does not have the 60C limitation that NM-B has. If all your terminations on the entire circuit are listed for 75C heat, then you can use the numbers in the 75C column of Table 310.16. Just make sure and look at the temp rating of the mini split terminations. You always have to figure your ampacity according to lowest temperature rating of any termination on the circuit.
 
Rick 0920 said:
MC cable does not have the 60C limitation that NM-B has. If all your terminations on the entire circuit are listed for 75C heat, then you can use the numbers in the 75C column of Table 310.16. Just make sure and look at the temp rating of the mini split terminations. You always have to figure your ampacity according to lowest temperature rating of any termination on the circuit.
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But otherwise #8 Romex MNB should work right?
 
Don't go down the path of over-specifying things for the electrician. Yes #8 NMB is a very likely solution in this situation, but that could change based on the specifics of the installation.

Forum rules explicitly prohibit providing DIY help. Since your original question was about confirming that there was a problem for an electrician to fix, we were able to help. But once we start trying to help you fix this directly, the post will get shut down. There are numerous details of an electrical installation, and there is no way that a forum post could anticipate all of the details that we'd assume an electrician knows and you don't even know to ask about.

-Jon
 
winnie said:
Don't go down the path of over-specifying things for the electrician. Yes #8 NMB is a very likely solution in this situation, but that could change based on the specifics of the installation.

Forum rules explicitly prohibit providing DIY help. Since your original question was about confirming that there was a problem for an electrician to fix, we were able to help. But once we start trying to help you fix this directly, the post will get shut down. There are numerous details of an electrical installation, and there is no way that a forum post could anticipate all of the details that we'd assume an electrician knows and you don't even know to ask about.

-Jon
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Totally understood just trying to learn the trade. 😊
 
mystycs said:
Just learning here what are the properties of THHN and MC that can handle it at #10 over #8NMB? Is metal clad not NMB with just a metal enclosure?
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Another thing that makes it more complicated is the "small conductor" rule in 240.4(D). That is where the common assumption that "#14 is 15A, #12 is 20A and #10 is 30A" comes from. That rule does not apply to HVAC installations.
 
I think the OP's question has been answered adequately. We can't go further without getting into DIY.
@mystycs
Come back and post what your electrician, or HVAC tech does, you will have to start a new thread at that time.
 
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