electrical help- what wire gauge to run ?
 

I have ordered a 24k mini split heat pump/AC and I need to run some 220 wiring. The manufacturer of the mini split recommends a 20 amp circuit breaker which I have already purchased. I haven't measured the length of the run but lets say its 70 ' probably closer to 50-60 . The manufacturer of the mini split states it only draws 11 amps at the very highest heat/AC setting. My searches on the net state that 12/3 wire is sufficient for 20 amps. Do you guys agree ? I don't know when you have to go down in wire size ( 10/3 ) due to the wire run length. What say the experts ?

There is no voltage drop at 70 feet.
If the total connected load is under 20 amps for a single phase 220 volt circuit then
a HACR 20 amp single throw, double pole breaker is fine.
No worrys dude.
HACR are designed for what you need. They take care of the starting current and don't trip. Every Hardware in America sells them.
Enjoy the new comfort.

#12 THHN

You will OK with 12/3 but if you are going to the trouble of burring it or there is a chance that some point you might require more power i.e needing 30 Amps, going to 10/3 is a bit more expensive but could be worth it.

Here is a calculator: Wire Size Calculator

The drop may be negligible (<3%), but there is a drop. (70' for 12AWG at 11 A is 2.9V or 1.2%)

I'd recommend 10AWG.

12/3 is enough, but if it's an easy run and you can fit 10/3, spend a few extra $$ and do it.

IMO

The run will be easy and I was just pricing solid THHN wire and the difference between #10 + #12 is not much. I will probably go with #10 to be ultra safe. Yes the breaker I purchased is a GE single throw double pole. Thanks guys.

why aren't you just going to run 12/2 (two conductors and a ground)

more than adequate to carry an anticipated load of 11 amps

Haha I fat fingered and didn't notice, you are correct two conductor and a ground not three conductor.

just remember that for a mini split you may have to run a 3 wire (three conductors and a ground) from the condensor to the wall unit. some units require two separate feeds, 240 out, 240 in with control wiring joining the two. check your specs first.

Good point as I have not received the mini split yet. I will check the specs once I receive it. But I was under the impression that the wires going from the outside unit to the inside unit were low voltage ? Right now I am just talking about the wiring going from the breaker box to the outside AC disconnect/pigtail.

something needs to carry the blower load inside

and check to see if you need a condensate pump inside

I just checked my order and the " install kit " comes with 15 ' of 14/4 connecting wire to go from the condensor to the evaporator. No need for a condensate pump.

simple enough, i assume the "4" is an insulated ground

Your code will probably state that you need to run 3 wire for 220V or make sure your two wire is black/red with ground. Some will allow you to run the black/white with ground but you have to tape the white wire as most consider it neutral and should not carry current. When I did install, I'd size the wire up one if it was marginal and put the smaller breaker on it. If I was in your position I'd install the 10/2 with ground and tape the white wire black on both exposed ends.

Do it once. Run 10 gauge.

And run 3 wire.

Many of these newer units need a separate neutral. Like dryer plugs, which are now 4 prong, and separate the neutral and ground.

If you don't need the neutral, just cap it and roll it up in the box.

Code is always changing, and local codes supersede NEC.

Carter

^^^^^ since your not sure play it safe and run a 3 wire with ground. Do it once it sucks to have to pull another wire. #10 3 wire/ ground

My mini split heat pump is just 12/2 , 60' run. Has been running flawless for 6 years.

Don't forget to add switches next to the units for maintenance. I think it's within 5' per code. I put a wall switch below and low for the inside unit and a switch on the junction box next to the outside unit.

The wall unit is 220v but probably not even 1 amp so 14 ga is more than enough for it.

Here it's one outdoor switch beside the unit.
The indoor units are fed by the outdoor units, the one switch shuts everything down.

So you have a single throw double breaker with two wires coming out of it correct ? Then the third wire is ground going from the box to the mini split right ? Sounds simple enough.

Part of the install kit I purchased includes a disconnect switch with pigtail that runs to the outside unit.

I received the mini split yesterday and I tore into the box to look at the main unit and find the install/owners manual. The 220v feed on the outside unit is two wires plus a ground. I'm pretty sure I'll go with # 10 solid THNN wire in red/black/green to be extra safe. So now I have a path forward thanks to everyone on the advice.