Delta Wye starter OCPD


Senior Member
Good day,

I have 320 hp load that comes with Delta Wye starter. I am trying to select OCPD. I am confused whether I have to pick a motor protected molded case breaker or thermal magnetic molded case breaker. I also wonder the size of the breaker. The voltage is 480 VAC. Feedbacks are welcome.

Thanks in advance.
Good day,

with Delta Wye starter.

Thanks in advance.
In case anyone else is confused by this. You do mean Wye Delta, right? Not Delta Wye

See article 430 part IV for general SC and GF protection of motors. Table 430.52 has sizes based on protection type. Is there another specific question you have?
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Staff member
If what you are asking is if you can select an MCP (magnetic - only) circuit breaker, the answer is, no. The only people that can use MCPs are control equipment manufacturers that use them as part of a factory tested and listed assembly. There is no valid use for them in field assembly as per the NEC other than directly replacing one-for-one with an exact part number within a factory assembled starter.

Just use a thermal-mag breaker and quit worrying about it. There is no special sizing necessary just because it is Wye-delta, use the NEC tables mentioned above.