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I'm having a 2-ton Lennox Split-System AC Model XC25-024-230-2 installed next week and would like to make sure I'm installing the electrical service correctly.

SPECS ON UNIT

  1. Voltage: 208/230V-1ph-60hz

  2. Maximum Overcurrent Protection: 25A

  3. Minimum Circuit Ampacity: 14.9A

  4. Distance from panel: approx 100 ft

ELECTRICAL INSTALL?

  1. Square D QO 25 Amp Two-Pole Circuit Breaker (HACR rated)
  2. 12-2 Solid CU UF-B W/G Cable
  3. Square D 60A (non-fused) Disconnect at unit

THANKS!

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Their specification of 12 AWG wire would be fine if the run was a lot shorter, and if you never foresaw upgrading to a bigger unit.

It squeaks under the 16A limit for continuous loads on a 20A circuit.

As such, I would use 10 AWG copper wire, as it is the industry standard for runs to an outside compressor unit (i.e. A bigger unit), and it will assure your electricity dollar goes to run the compressor rather than heating up 12 AWG wire.

I would then use a 20A circuit breaker. A 30A would be allowed on 10 AWG wire, however the instructions prohibit this and seem to advise a 20A or at maximum a 25A breaker. Listing, labeling and instructions must be followed; the electrical code requires this.

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  • We are foam insulating the entire house and downsizing from 3.5-ton unit so I do not anticipate upgrading to a bigger unit. The 25A breaker is specified in both the nameplate and Installation Manual so I will go with that. I was concerned about the length of the wire run. I will upsize to 10 AWG per your suggestion. I assume using UF-B outdoor wire is correct even though the only place it is "outdoors" is where is penetrates the wall and enters the disconnect?
    – ftelliott
    Apr 19 '17 at 15:16

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