Air Conditioning Wire Sizing

[JesseETG]

I am aware that you size Air conditioner conductors based off the Minimum circuit amps on the nameplate of the unit. However do you add the 125 percent continuous load adjustment to size your wire ?
The air conditioner may possibly run for more than three hours on a hot day I would assume.

 

[LarryFine]

However do you add the 125 percent continuous load adjustment to size your wire ?

Negatory, morning glory. That's all figured into the MCA already.

 

[infinity]

Yup, what Larry said.

Negatory, morning glory. That's all figured into the MCA already.

 

[Dennis Alwon]

I am aware that you size Air conditioner conductors based off the Minimum circuit amps on the nameplate of the unit. However do you add the 125 percent continuous load adjustment to size your wire ?
The air conditioner may possibly run for more than three hours on a hot day I would assume.

It doesn't really matter if the unit runs for 3 hours or not because all motors must be sized at 125% for the conductors.

 

[jap]

Negatory, morning glory. That's all figured into the MCA already.

"Negatory pig pen it's clean clear to Flagtown come on",,,,

JAP>

 

[Lucia1222]

Where I’m am from in Pittsburg I feel like nobody knows this I kinda see it as a problem that even tech support for the air conditioners we sell don’t know this I think the person training doesn’t know then the manufacturer should have to put it in manual list the code or something I have 2 electricians that said it’s wrong the electric supply store said it was wrong but trying to prove this that don’t believe it is impossible I tried 3 different tech support guys all told me I was wrong about sizing wire for ac to mca

 

[mtnelect]

This might help explain.

 

[Lucia1222]

That will help I think I’m the young guy in the room here this argument didn’t go so well for me in a class of 10 people none of them agreed lol thank you

 

[mtnelect]

That will help I think I’m the young guy in the room here this argument didn’t go so well for me in a class of 10 people none of them agreed lol thank you

HVAC is a specialty and doesn't follow common motor calculations. Of the most common questions asked on this site and the most misunderstood is HVAC.

 

[LarryFine]

Show them NEC 240.4(G), and 440 parts III and IV that it directs you to.

HVAC and other motor loads are permitted to exceed normal ampacities to allow for starting currents, and because those loads contain their own over-current protection, and the breakers protect against shorts.

 

[Lucia1222]

HVAC is a specialty and doesn't follow common motor calculations. Of the most common questions asked on this site and the most misunderstood is HVAC.

That’s where my issue is I’m installing it I need to know the correct rules if a smart customer calls me out and I don’t the right answer I’m the one who looks like a idiot now the manufacturer pays people to train on that equipment they should be teaching the correct thing not just telling me I can’t put 10 wire on a 40 Im willing to say at least half or more of the techs in my area do not know this there’s a possibility that half the electricians don’t either thank for the help I appreciate it

 

[Lucia1222]

Show them NEC 240.4(G), and 440 parts III and IV that it directs you to.

HVAC and other motor loads are permitted to exceed normal ampacities to allow for starting currents, and because those loads contain their own over-current protection, and the breakers protect against shorts.

I’m working that but when you try to show your boss and the guy your boss trust it’s like they just went deaf

 

[texie]

My experience tells me that there are millions of A/C condensor units installed with conductors that a are much larger than required. All do to a lack of understanding of the NEC and NRTL requirements. This goes for both the electricians and the AHJ folks. Sad indeed and also just increases costs unnecessarily.

 

[mtnelect]

That’s where my issue is I’m installing it I need to know the correct rules if a smart customer calls me out and I don’t the right answer I’m the one who looks like a idiot now the manufacturer pays people to train on that equipment they should be teaching the correct thing not just telling me I can’t put 10 wire on a 40 Im willing to say at least half or more of the techs in my area do not know this there’s a possibility that half the electricians don’t either thank for the help I appreciate it

This is a great resource for all Electricians. Mike Holt teachings are known world wide.

 

[Lucia1222]

My experience tells me that there are millions of A/C condensor units installed with conductors that an are much larger than required. All do to a lack of understanding of the NEC and NRTL requirements. This goes for both the electricians and the AHJ folks. Sad indeed and also just increases costs unnecessarily.

I’ve watch people rip out the wire that would’ve been fine re run it bigger instead of just changing the breaker

 

[Lucia1222]

This is a great resource for all Electricians. Mike Holt teachings are known world wide.

He should come to Pittsburgh area supply houses and teach the hvac industry because most shouldn’t be allowed to plug in a vacuum

 

[mtnelect]

My experience tells me that there are millions of A/C condensor units installed with conductors that a are much larger than required. All do to a lack of understanding of the NEC and NRTL requirements. This goes for both the electricians and the AHJ folks. Sad indeed and also just increases costs unnecessarily.

In California, no more "Rule of Thumb", Heat Load Engineering Study" are now required. See Attachment

 

[LarryFine]

. . . not just telling me I can’t put 10 wire on a 40 . . .

Tell them you're putting #10 wire and a 40a breaker on the circuit to a piece of equipment that specifies a conductor capable of 30a and a breaker of 40a.

 

[Lucia1222]

Tell them you're putting #10 wire and a 40a breaker on the circuit to a piece of equipment that specifies a conductor capable of 30a and a breaker of 40a.

lol that’s what I’m doing from now on this forum would’ve saved me so much time proving this

 

[texie]

In California, no more "Rule of Thumb", Heat Load Engineering Study" are now required. See Attachment

What does this have to do with conductor sizing to an A/C condenser ?