Feeding 2 breakers on A/C unit

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storeytime

storeytime

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Texas
Most air conditioner/heat strip/ blower motor units (indoor/residential/1 phase)around here have two breakers on them. Usually a 2P 30 and a 2P 60. The A/C people almost always ask me to run one larger wire--hit the 60 amp breaker--tap off the 60 with #10 to the 30amp breaker. I know you can't double up under the 60 amp breaker. But even if I hit a J box and made joints, this would still be an illegal tap wouldn't it? I have always run #6 from a 2P 60 in the panel to the 2P60 on the unit and #10 from a 2P 30 in the panel to the 2P 30 on the unit. This seems redundant. Is there a better, legal way?
 
Re: Feeding 2 breakers on A/C unit

I believe the installation you describe complies with the tap rules and is OK. Just be sure the No. 10 conductors are in a raceway. But I'm not the sharpest knife in the drawer so someone else may correct me if I'm wrong.
 
Re: Feeding 2 breakers on A/C unit

I would have no problem doing this under the tap rules. Make sure your feeder conductors are sized per Art. 440.

I know HVAC/R techs would rather have one breaker to kill a unit for service purposes. The only advantage to having the 2 breakers in the unit is if you lose a heat bank, you can always limp along on one.
 
Re: Feeding 2 breakers on A/C unit

More often than not, these breakers in these HVAC units are Square 'D' QOU universal din rail mount type breakers. You can jumper two of these breakers with Square 'D's QOU14100BAF jumper bar assembly. This jumper has a set of lugs that will take #14 through #2/0 conductor to feed both breakers.
 
Re: Feeding 2 breakers on A/C unit

I have just been told by the A/C contractor that the two breakers on the A/C unit are not breakers, but molded switches. The one marked 60 switches 3 - 5kw heat strips and the one marked 30 switches 1 - 5kw heat strip and the motor, So I need to figure out how much to fuse, and wire size it based on that. Thanks everyone for your help.
 
Re: Feeding 2 breakers on A/C unit

Originally posted by storeytime:
I have just been told by the A/C contractor that the two breakers on the A/C unit are not breakers, but molded switches. The one marked 60 switches 3 - 5kw heat strips and the one marked 30 switches 1 - 5kw heat strip and the motor, So I need to figure out how much to fuse, and wire size it based on that. Thanks everyone for your help.
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Doubt what you've been told.

They are most often QOU breakers. Molded switches don't have number molded in the handles.
 
Re: Feeding 2 breakers on A/C unit

Originally posted by mdshunk:
More often than not, these breakers in these HVAC units are Square 'D' QOU universal din rail mount type breakers.
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I also hold an active Journeyman A/C license. I have replaced several of those QOU breakers. We just supplied new feeders to a 20KW furnace replacement (was a 15KW with aluminum conductors) for my A/C Contractor buddy, that had 2 2P60's. Rather than run a 1/0 to it, I ran separate 6/2 NM. Though I have used the tap rule, sometimes separate feeds are more convenient.
 
Re: Feeding 2 breakers on A/C unit

I went today and looked for myself. You're right. They are breakers and not molded switches.
Thanks for the replies.
 
Re: Feeding 2 breakers on A/C unit

Around here, the concensus is that, if the breakers are externally accessible, you don't need a separate disconnect, if that's any help.
 
Re: Feeding 2 breakers on A/C unit

This is more of a code issue than a contracting issue. I am moving it to the NEC topic area.
 
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