Breaker for PTAC

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electricalintern

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PA
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Intern in Highschool
If the existing breaker is 30AMP/240V/1P and the nameplate for the new PTAC only requires 20AMP/240V/1P.

Is it okay to keep the existing 30AMP breaker and connect the new 20AMP PTAC unit load to the existing 30AMP Breaker.

Or it it better to swap out the 30AMP breaker with a 20AMP breaker.

Reason why I ask, will this be a fire hazard since the 30 AMP breaker will never trip
 
Does the nameplate say max breaker or fuse...? If so, you cant exceed that and need to change the breaker if max breaker is less than 30.
 
electricalintern said:
Yes, the nameplate says max fuse size is 20 AMP.

But doesn't all nameplate always give the max fuse size?
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If the nameplate says "max fuse size" and doesn't give a max breaker size, then you need to provide a fused disconnect with 20 amp fuses. Once you do that, the conductors from the panel to the disconnect become feeders and must be sized per 310.16 (or 310.15 depending on code cycle). The conductors beyond the disconnect become a the branch circuit and are allowed to be sized per chapter 4.
 
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