On this page 3 sections
Compressors surge — the circuit, the starter, and a disconnect that hold through start
Compressors surge. The circuit, the starter or drive, and the disconnect have to be listed for that. Sharing a compressor with lighting or a general receptacle circuit will nuisance-trip mid-shift.
A generic motor
A motor that is not a compressor is motor circuits.
A refrigeration rack
Walk-ins, cases, and the rack as a system are refrigeration equipment feeds.
The rest of the floor
Shop machinery that is not a compressor is machinery circuits.
A hermetic compressor is sized off its own nameplate, not a horsepower table
A sealed compressor is not a general motor. Its nameplate gives rated-load and locked-rotor amps and a maximum overcurrent device — and that maximum, not a horsepower rule of thumb, sizes the protection.
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RLA and LRA, not HP
Rated-load amps set the conductors; locked-rotor amps set what the circuit survives at start. A compressor sized from a horsepower chart trips or under-protects.
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A maximum device on the plate
The nameplate names a maximum fuse or breaker size. Exceeding it to stop nuisance trips is how a stalled compressor becomes a fire, not a fix.
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Start assistance
Hard-start kits and the right starter or drive are the answer when it will not start — not a bigger breaker on the same tired winding.
When a compressor circuit isn’t the right job
The compressor and its start are this job. A generic motor, or the whole refrigeration rack, are not.
It is a motor, not a compressor
That is motor circuits.
The whole refrigeration rack is the job
That is refrigeration equipment feeds.
Compressor circuits questions
It trips on start.
That is surge. The circuit and the starter have to be listed for the compressor that is actually there — not for the last one that came out.
Is this the same as a motor circuit?
A compressor is a motor with a start problem of its own. A generic motor is motor circuits. This job is the surge.
It feeds a walk-in rack.
The rack as refrigeration — walk-ins, cases, dedicated cold — is refrigeration equipment feeds. A single compressor landing is this job.
Can it share with the shop lights until we pull a new circuit?
No. Sharing a compressor with lighting is a trip at shift change, and it is not protection for the winding.
What size breaker do I need for a 220 compressor?
The breaker needs to match the specs on compressor nameplate and the motor starting current.
Still not sure it is the right job? Call (279) 972-9272 — available 24 hours.
Serving 19 communities across the Sacramento area
Litel Electric serves businesses throughout all 19 communities in our service area — from Davis and Woodland to Roseville, Folsom, and Elk Grove.
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We reply with what it involves and what has to be seen in person.
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