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In our previous issue, we discussed the fact that you can exceed the maximum overcurrent protection device (OCPD) sizes provided by Table 430.52 if the table limits don’t permit starting the motor. But the exceptions have limits, too.
It’s unlikely you’ll get to a situation where the exceptions noted in 430.52(C)(1) aren’t enough to let you proceed. But what if you do? You’ve reached the limits permitted by the NEC and still your motor won’t start.
Probably, something is wrong. Some possible issues:
So inspect the motor system. Correct any deficiencies, and then try again using Table 430.52.
If you’ve done the preceding steps but still can’t start the motor using an OCPD within NEC limits, contact your electrical distributor about a soft starter or motor drive for it. Either one is a good investment that provides other advantages beyond just meeting OCPD requirements.