Trying to figure out proper breaker size for mini split.

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Old 10-04-19, 10:29 PM
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Trying to figure out proper breaker size for mini split.

Working on installing a 24k Mr. Cool (Advantage, not DIY, kit). The install manual is more like vague suggestions more than anything else. Seriously, they are pretty terrible.

In the manual sort of alludes to the fact that I would use a 30 amp 240 breaker with #10 wire. Well, I was already going to use #10 THHN through EMT as I have enough sitting in my shop to use.

I was also a little confused if I needed to use a fused or non-fused disconnect. I researched for awhile and while I'm not sure why I landed on this, I decided to go with a non fused disconnect.

Then I read the sticker on the unit and it seems to be saying I may need a 25a breaker.

According to the label:

Compressor Load: 15.0A
Minimum Circuit Ampacity: 20.0A
Max Fuse: 25.0A

Also, I read that to determine if you are to use a fused disconnect or non-fused, if this label actually says the word fuse, it is recommending a fused disconnect. Is that accurate?

I may be thinking too hard about this. Will I be fine with a non-fused disconnect, #10 conductor, 30A breaker? Or the same, but with a 25A breaker. Or, should I use a 30A breaker, #10 conductor, with a fused disconnect with 25A fuses in it?

Thanks!

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Old 10-05-19, 09:01 AM
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Minimum circuit ampacity means that at least #12 needs to be used. #10 is fine too.
Maximum fuse size can be a breaker or fuses.

You could run #10 wiring on a 30A breaker and then use a fused disconnect with 25A fuses.
You could run #10 wiring on a 25A breaker and then use a non fused disconnect.

I wouldn't protect the split unit any higher than 25A..... even though code says a 30A breaker could be used if a 25A breaker was not available.
 
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Old 10-05-19, 09:05 AM
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Thanks for the response. In the instance I use a 30a breaker and a 25a fuse, should the fuse be time delay in this instance? Seems that would make sense due to kick on surge. Or even a 20a time delay?
 
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Old 10-05-19, 09:09 AM
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20A time delay or 25A standard would be fine.
 
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