Disconnect Switch wiring

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Old 12-25-17, 09:48 PM
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Disconnect Switch wiring

My disconnect switch is for a mini-split outside unit, that calls for maximum 20A fuses. Because the mini-split is a two ton unit it may use more than 20A on start up, so I will be installing slow blow fuses in the switch. For the short run of wire from the disconnect switch to the outside condensing unit, I will be using 12 gauge wire. My question is it ok to also use 12 gauge wire for a seventy foot run from the electrical panel to the switch, or is it more acceptable to use 10 gauge wire even though there isn't that much less of a voltage drop with 10 gauge? With 245v on both legs that my power company is pushing to my main electric panel, I would still have 235v at the condensing unit, but I'm concerned that an electrical inspector may expect 10 gauge wiring because of the compressor.
 
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Old 12-25-17, 10:02 PM
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Using 20A slow blow fuses is fine.
You're still using a 20A circuit breaker in the main panel..... correct ?

With a 70' run from the panel to the disconnect.... I'd recommend and personally use the #10 cable. There are some that don't feel as I do but I prefer not starving a compressor for power.
 
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Old 12-26-17, 05:31 AM
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The data plate on the unit will state the minimum circuit capacity and maximum overcurrent size . Follow those requirements.
 
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Old 12-26-17, 07:25 PM
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Pete,
Thanks, for your quick reply. Yes, I will still use a 20A circuit breaker at the main panel, along with the 20A slow blow fuses at the disconnect switch. Also I will definitely take your advice and order # 10 gauge wire, for the 70 foot run.

Thanks
 
 

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