Wire gage for an AC condensing unit?

[RonRock]

I'll probably get my *** handed to me over this question but here goes.

I'm relocating the AC condensing unit from the driveway side to the other side where it should have been. Small unit small house. The unit is labled that says to fuse or HACR type circuit breaker no bigger than 20 amps.
So I figure a 20 amp circuit 12 gage wire. Correct? Or do I need to go to 10 gage with an AC unit and still use a 20 amp breaket?

30 feet max from bteaket box to unit.

I'll be running conduit from breaker box to outside AC disconnect.

 

[Norcal]

What does the label say as to the minimum circuit size? But 12 AWG on a 20A circuit looks to be fine.

 

[RonRock]

Good point. I should have mentioned that.

Minimum circuit amps 12.5.

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[Aceman]

#14 on a 20 amp breaker would be to code. If you wanted to run #12 that would be fine too, but there would be no benefit.

 

[wyliesdiesels]

For AC units, wire is sized by the MCA(minimum circuit amps) and breaker is sized by the MOCP(max overcurrent protection).

Post a pic of the nameplate label

Doesnt get any easier than that.

 

[RonRock]

I hope this can be read.

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[RonRock]

Thanks guys. I'm glad I asked.

Good explanation.

Counter to my way of thinking. My thoughts were on the 20 amp max. And the unit running for long times in the hottest conditions.

10 gage! What an idiot!

I'll use 12 gage. And learned something about why.

Cheers.

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[Norcal]

With A/C equipment you wire for the minimum, & use fuses or circuit breakers rated for the maximum, no need to do the normal 125% as it's already been done.

 

[Bert_]

According to the nameplate #14 on a 20a breaker would be fine. Larger wire is fine but overkill. Breaker does need to be a 20A.

The 12.5A number is already 125% of running amps. Compressor + fan = 10.3A full load for this unit.

Larger breakers than normal for a wire size are normal in motor circuits.

 

[wyliesdiesels]

Thanks guys. I'm glad I asked.

Good explanation.

Counter to my way of thinking. My thoughts were on the 20 amp max. And the unit running for long times in the hottest conditions.

10 gage! What an idiot!

I'll use 12 gage. And learned something about why.

Cheers.

Sent from my SM-G930V using Tapatalk

#14 on a 20a breaker is all you need.

Unit draws 10.3a...

 

[brewchief]

With AC units I like to see a little bit of forward thinking, if a unit is close on wire size on the min ampacity and the larger wire isn't going to be a major cost increase I like to see it upsized. A unit that is listed at 14.5 min could easily get replaced with a same size unit of a different brand that may not really pull any more power but has a min of 15.2 and you are replacing the wire.

 

[Norcal]

With AC units I like to see a little bit of forward thinking, if a unit is close on wire size on the min ampacity and the larger wire isn't going to be a major cost increase I like to see it upsized. A unit that is listed at 14.5 min could easily get replaced with a same size unit of a different brand that may not really pull any more power but has a min of 15.2 and you are replacing the wire.

The OP is using conduit to supply unit so 14 AWG THWN is good for 20A.

 

[donpauli2]

Since when is #14 rated for 20 amps


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[alfredeneuman]

Since #14 is rated for 20Amps at 75 degrees C.
Motors and AC compressors are exempted from the usual limits for #14,(15) #12,(20) and #10 (30).
As long as the terminals are rated for the temp involved you're good to go.

 

[DC73]

Counter to my way of thinking. My thoughts were on the 20 amp max. And the unit running for long times in the hottest conditions.

Another thought. Does your AC unit cause your lights to dim briefly when the compressor engages? If so, stepping up in wire size could help minimize or even eliminate the dimming.

DC

 

[brewchief]

The OP is using conduit to supply unit so 14 AWG THWN is good for 20A.

I missed the conduit part but wasn't really thinking about the OPs specific case anyway, just what seems to happen in some cases.

 

[Bert_]

Since when is #14 rated for 20 amps


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It's not, the unit draws 10.3A...

The 20A breaker is needed to prevent tripping on startup due to high inrush current. This is inherent to all motors. The code make allowances for this by allowing us to size the wire to the full load, and size the breaker to handle the inrush.