# wire size for air conditioner



## robgibson73

It says max fuse size is 25 amps. What size wire should I use. I can remember but I think I need to up size my wire 1.25% . Can someone please help me on this.


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## Legacyelectric

What's minimum circuit ampacity?


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## bkmichael65

robgibson73 said:


> It says max fuse size is 25 amps. What size wire should I use. I can remember but I think I need to up size my wire 1.25% . Can someone please help me on this.


Not sure about Canada, but here you would use the nameplate info for the minimum circuit ampacity for conductor sizing


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## FrunkSlammer

Without knowing anything whatsoever.. pull #12 and put it on a 20A breaker.

Now pay me my $100 consultation fee.


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## robgibson73

What do you need to know. It's only about 50ft away from the breaker. I think there might even be a 30 amp breaker already installed. 
My question is. Do I need to up size the wire and breaker because it's an AC unit. Just as you would for a motor.


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## daveEM

Well if it says max size 25 amp do toss the 30 that's in there.


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## Dennis Alwon

robgibson73 said:


> What do you need to know. It's only about 50ft away from the breaker. I think there might even be a 30 amp breaker already installed.
> My question is. Do I need to up size the wire and breaker because it's an AC unit. Just as you would for a motor.


The minimum circuit ampacity (MCA) listed on the unit will have the 125% already built in.


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## robgibson73

Thanks for all of your help. I appreciate it.


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## A Little Short

robgibson73 said:


> Thanks for all of your help. I appreciate it.


Do you now know what to look for?

MCA (minimum circuit ampacity)

Max fuse or breaker size

You don't size the wire per the breaker/fuse on HVAC equipment.

What does the MCA say on the nameplate?


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## Anthony young

If your max overcurrrent is 25A then your minimum circuit ampacity should be around 16A or somewhere in that area. So you just go to the next standard wire size which will be #12 for 20A. The 25A max is just for startup and after that the unit will draw the minimum circuit ampacity so #12 will be the correct wire size for this application.


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## Jack Legg

Anthony young said:


> If your max overcurrrent is 25A then your minimum circuit ampacity should be around 16A or somewhere in that area. *So you just go to the next standard wire size* which will be #12 for 20A. The 25A max is just for startup and after that the unit will draw the minimum circuit ampacity so #12 will be the correct wire size for this application.


you don't have to go to the next standard wire size

your conductor just has to handle the min ckt ampacity


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## erics37

Jack Legg said:


> you don't have to go to the next standard wire size
> 
> your conductor just has to handle the min ckt ampacity


Yeah, find me the conductor size in 310.15(B)(16) for 16 amps.


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## dcb_minded

erics37 said:


> Yeah, find me the conductor size in 310.15(B)(16) for 16 amps.


16amps = 16 gauge, right? 

Sent from my SGH-T599 using Tapatalk


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## erics37

dcb_minded said:


> 16amps = 16 gauge, right?
> 
> Sent from my SGH-T599 using Tapatalk


erm..... :blink:


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## Jack Legg

Anthony young said:


> If your max overcurrrent is 25A then your minimum circuit ampacity should be around 16A or somewhere in that area. So you just go to the next standard wire size *which will be #12* for 20A. The 25A max is just for startup and after that the unit will draw the minimum circuit ampacity so #12 will be the correct wire size for this application.





erics37 said:


> Yeah, find me the conductor size in 310.15(B)(16) for 16 amps.


it aint #12


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## erics37

Jack Legg said:


> it aint #12


I see where you're comin' from. My bad.

#14 is good for 20a for the A/C circuit. I thought you were saying he could use wire rated for 16 amps max, which he could, but what size would that be? 15½ gauge? :laughing:


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