What size wire does an air conditioner take to run?

When deciding the wire gauge for a residential application, there are only two things that matter, one being the amperage and the other is the distance.

Assuming a normal residential application we can probably ignore the distance, but you MUST know the amperage that the AC will be using.

If the AC does not list the amperage, just know that you can always refer back to the math that you learned in school.

A simple algebraic formula will help you figure out the amperage:

Amps * Volts = Watts

Since you already know the Volts (use 120 for calculation), you should be able to calculate the amperage that is used by the AC.

Up to about 12 Amps, use a 15 amp breaker and 14 AWG wire.

Up to about 16 Amps, use a 20 amp breaker and a 12 AWG wire.

Up to about 24 Amps, use a 30 amp breaker and a 10 AWG wire.

You should have a qualified electrical professional perform any wiring changes if you do not have an adequate circuit already available to the AC and need to modify the current wiring of your home.

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The above answer is correct except that you want to use 240v for the calculation and if you do not find watts on the AC nameplate you might find volt-amps. Substitute volt-amps for watts and do the math as described.

As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.

Before you do any work yourself,

on electrical circuits, equipment or appliances,

always use a test meter to ensure the circuit is, in fact, de-energized.

IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB

SAFELY AND COMPETENTLY

REFER THIS WORK TO QUALIFIED PROFESSIONALS.