Electricalhelp
Senior Member
- Location
- NJ
Condensing Unit Breaker Size
- Thread starter Electricalhelp
- Start date
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mtnelect
HVAC & Electrical Contractor
- Location
- Southern California
- Occupation
- Contractor, C10 & C20 - Semi Retired
Follow the manufacturer's recommendations ... The work is already done for you.
This always trip people up ... the compressors are cooled by the suction line return and don't pull as much amps as standard motors. A hermetic compressor is a sealed unit with compressor and motor together.
The label has the Minimum Circuit Ampacity (MCA) and max breaker sizes specified. That is all you need. Since it is 208V, it would be a 2 pole 15A breaker.
The Locked Rotor Amps LRA is rarely used except when checking the size of a generator or transformer feeding the service or feeder.
The Locked Rotor Amps LRA is rarely used except when checking the size of a generator or transformer feeding the service or feeder.
Electricalhelp
Senior Member
- Location
- NJ
So I ever do a load calculation for new service for a building, I should use the LRA load
No. However, the power company may ask what your highest LRA motor is when selecting the transformer to feed that service (the transformer needs to be large enough to supply that LRA). Or if it an industrial site and you have your own transformers and distribution, you'd need to look at transformer size when there are larger motor loads.
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