AC feeders

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jwelectric

Senior Member
Location
North Carolina
Based on statements read in this forum I wasn?t sure how to answer the following question ask by a student so I ask the DOI in Raleigh.

Mitch,
I have a question about feeders for a outside AC unit.

This is how I answered this question.

430.62 Rating or Setting ? Motor Load.
(A) Specific Load. A feeder supplying a specific fixed motor load(s) and consisting of conductor sizes based on 430.24 shall be provided with a protective device having a rating or setting not greater than the largest rating or setting of the branch-circuit short-circuit and ground-fault protective device for any motor supplied by the feeder [based on the maximum permitted value for the specific type of a protective device in accordance with 430.52, or 440.22(A) for hermetic refrigerant motor-compressors], plus the sum of the full-load currents of the other motors of the group.

Using this section of the code I made the statement that the conductors between the breaker in the panel and the required fused disconnect at the unit could be the same as marked on the unit.

After thinking about my answer I though it would be a good idea to ask for help.
The Min.Cir. Amp marked on the unit is 17 amps but it is also marked with Max Fuse Size 40 amps.

#12 is isntalled from the panel to the outside fused disconnect.

My question is;
being that the conductors from the breaker to the disconnect are feeders will they be required to sized to 40 amps?


Thanks
Mike Whitt

Here is the reply I got from the DOI in Raleigh.

Mike, your basic answer is correct, but to clarify one must look at 240.4 (D) rules for small conductors. Which tells you that the rules apply except when used as in 240.4 (E) and (G) which includes A/C and refrigeration 440 parts 3 and 6.
So in the case you described #12 AWG would meet the requirements of the NC Electrical Code.
Thanks

I thought it might be good to pass it along to this thread as a lot of the members are located in the great state of NC.
 

tshea

Senior Member
Location
Wisconsin
bphgravity said:
Whats a "DOI" ?

Department of Insurance

Your example of the AC feed is correct. I educated one of our inspectors years ago after he "gigged" us for a #12 on a 40A breaker. He apologized and then thanked me. We get along well. We have mutual respect for each other!
 

jwelectric

Senior Member
Location
North Carolina
bphgravity said:
Whats a "DOI" ?

In North Carolina the Code Officials Qualification Board is a division of the Department of Insurance Office of the State Fire Marshall. The Chief Electrical Inspector works for the Department of Insurance. He if the person whom we address with questions as to the Interpretations of code sections.

http://www.ncdoi.com/OSFM/Engineering/COQB/engineering_coqb_home.asp

A record is kept of different code interpretations and used through out the state for a more uniform inspection.

I am proud to say that in North Carolina the Office of the DOI is open to the public and any one can seek information from them. This is one way that we keep them inspectors on their toes.
 

RUWired

Senior Member
Location
Pa.
My question is;
being that the conductors from the breaker to the disconnect are feeders will they be required to sized to 40 amps?


I thought we discussed earlier that these were branch circuit conductors, not feeder conductors
Rick
 
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