Wire Amp size in Garage

[Deere Dude]

I have added a garage/tractor storage to my house. I am putting an overhead heater in; no problem. I want to put a wall AC unit roughly 18000-24000 BTU/H. I don't have a unit picked out yet, but expect it to be 220V. What size amp draw would that size AC take for 220. I understand it is all a guess especially without having an AC unit in hand.

I am dry walling right now so I need an educated guess. I have all kinds of 12-3 wire laying around and a small amount of 10-3 and a lot of 8-3. My lightly educated guess would be a 12-3 wire.

I looked at AC units on line but can't find any that say their amp rating.

Thanks,
Chuck

 

[s219]

The only data point I can share is that my PTAC unit is 15,000 BTU and runs on a 20A 220V circuit.

 

[davesl708]

It will depend on your wire run length. If 20 amp circuit and less than 75' wire run length 12ga. will work. If 30 amp load same run length then 10ga. would be required. Best bet is to check your local code requirements. Local codes vary. Current NEC is 2014.
Consider if you will be using the outlet for other equipment and size the load based on that and possible future demands.
Never hurts to go one wire size over base requirement.

 

[radioman]

the online tools if using 50 ft with 14 amps gives you 14 gauge minimum with 240v. I would not. It will not fly with code . I would use 10/3.

 

[PILOON]

12-2 can handle 20 amps on 110 circuits so at 220 you should be good with 12-3 .

The other option would be to install a sub panel in the garage using your 8-3 as the feed from the main panel. You would protect the feed line at main panel with appropriate breaker and the sub panel would feed garage circuits where I would wire with 12 g. for power tools.
Having garage sub panel 8-3 fed would allow welding, air, heat, compressor and just about whatever eventuality.

In a situation such as you propose I like lighting circuits to be independent from any outlets that could be used for tools as popping a breaker then does not leave you in the dark.

 

[uglyboywith11fingers]

my outside 2 ton (24000 btu) unit is fed off a 20a breaker and about 25 feet of 12-2.
I guess the blower must be a 220v motor as well.

Pete

 

[2458n]

Your going to break something in the future and will need a stick welder. Same thing you are going to want to paint something in the future-air compressor. Run a sub panel using the 8 gauge and be done with it. Someone will want it this way. Do it now and you will not regret it.

 

[LD1]

Does the A/C unit also have an electric heater built in.

I have a 220v unit I used in the shop. I believe it was 20,000BTU or so like you are looking. Nameplate said AC FLA was something like 6 amps. But the electric heater was more like 19A

 

[Deere Dude]

my outside 2 ton (24000 btu) unit is fed off a 20a breaker and about 25 feet of 12-2.
I guess the blower must be a 220v motor as well.

Pete

I am in the process of running a 100 Amp panel into the building but was mainly wondering about a stand alone AC. I remembered I have another AC in an outbuilding that is 220v 22,000 BTU/H and That says 18 amp or close to it so I should be good with 12 gauge wire, because a new unit should be more efficient that my old one. The run is about 30 feet and the building is well insulated so I'll go with that and make sure the AC is small enough for 20 amp 220v.

Thanks for the help guys.
Chuck

 

[Sawyer Rob]

Even though #12 wire is rated for 20A, the wire should NOT be loaded to more than 80% capacity, for continuous duty, and that's why I'd go with #10 in this case...

SR