AAC Disconnect

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tomito

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Mexico
Hello guys, I have a question that somebody else asked me, can a OCPD (lets say a 60 A CB) be used as an air conditioner disconnect (instead of a non fused disconnect) if the AAC ask for MOCP of 60 A, couldn't find anything on 440.11 B, or I didn't look hard enough.

Thanks
Tom
 
Just make sure your equipment doesn't specify "fuse protection". Some HVAC equipment is not listed for other than fuse.
 
If the source branch circuit is providing the overcurrent protection and is not above the max OCPD specified, then you can use a non-fused disconnect, or a fused disconnect. The fused disconnect could be 200A if you want, as you are not relying on the fuses since the branch circuit source is providing that. Likewise, if you had a 70A branch circuit and then had to install an AC unit with a max OCPD of 60A, you would need a fused disconnect rated 60A or less.
 
tomito said:
Hello guys, I have a question that somebody else asked me, can a OCPD (lets say a 60 A CB) be used as an air conditioner disconnect (instead of a non fused disconnect) if the AAC ask for MOCP of 60 A, couldn't find anything on 440.11 B, or I didn't look hard enough.

Thanks
Tom
Click to expand...
The MOCP means somewhere in the supply circuit to the equipment, you need an OCPD that's that value or less. Usually for motor loads, you want it as high as allowable to avoid nuisance tripping on inrush current.

You can have additional redundant fused disconnects or breakers that are either the same as that, or larger, to take the place of an unfused disconnect. The smaller OCPD is the weak link in the chain that does the job to trip on overcurrent, and the larger device remains in its normal state.
 
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