Wire size needed

[LarryFine]

If that ever happened the NEC would not allow this rule.

Well, that depends on your definition of "ever."

 

[qcroanoke]

That's silly. If you truly understand why it is okay to wire an a/c with a smaller wire than the OCPD, then you wouldn't worry about the building burning down. If that ever happened the NEC would not allow this rule.

From my earlier post:
It most likely wouldn't but when the building could be hundreds of mile away from where it was manufactured and people are pointing fingers we don't want them pointing at us. We've actually had customers call us and want to know how we could install an A/C unit with undersized wires from the factory in them!
Example: MCA is 60. We found a wire from the factory that couldn't have been much bigger than a #10! That must be why the compressor failed! We're not paying for this!
Then we have to explain we have no control over what the factory uses and it is all legal because it has a UL label on it.
It just ain't worth it......

Dennis, I truly understand why it is ok to use smaller wire.
And I never said I was worried about the building burning down. I said we try to avoid having fingers pointed at us.
We size our ACH feeds to the breaker size.
most of our buildings are less than 40 feet long so if pulling #8 when we could have pulled #10 will save us the grief of explaining to our customers that "it's to code" When they don't truly understand why it's ok,Silly or not that's what we will do.

 

[ceb58]

Unless the highway patrol has a building in Angola you're safe! :grin:

I wouldn't put it past them to try and put one there I just hope Angola is in the western part of the state, I have enough to do.

It most likely wouldn't but when the building could be hundreds of mile away from where it was manufactured and people are pointing fingers we don't want them pointing at us. We've actually had customers call us and want to know how we could install an A/C unit with undersized wires from the factory in them!
Example: MCA is 60. We found a wire from the factory that couldn't have been much bigger than a #10! That must be why the compressor failed! We're not paying for this!
Then we have to explain we have no control over what the factory uses and it is all legal because it has a UL label on it.
It just ain't worth it......

I will say I agree with Mike's reasoning. When something fails at one of the sites it is usually a communication tech. that finds it. There is a big difference between a communication tech. and a electrician for the most part. They look for any thing they think caused their radio equipment to act up.
Every thing I have seen pre installed in the buildings we get is code compliant and of good workmanship.

 

[hotwire1955]

The "Mnimum Circuit Ampacity" is 17. The ampacity of #12 THHN is 25, and that exceeds the minimum. Yes, you can use #12.

#12 THHN copper is 30 amps #14 thhn would be ok for a single motor compressor wiring start to finish, if you use nm or ac cable #14 is to small, it needs to be 125% of either compressor rated load current or the branch circuit selection current which ever is greater.