EGC serving motor

[Bea]

When up sizing over-current device of motor for high in rush does the EGC have to be increased what code reference support your answer.

Example a 208 volt 2 hp single phase motor minimum circuit would be 16.5 so provide 12 AWG conductors but will not start and run on 20 amp over current device so increase to 30 amp inverse time circuit breaker does the EGC have to rate on the 30 amp breaker.

 

[iwire]

In some cases you can base the EGC on the rating of the motor overloads instead of the short circuit / ground fault device.


2002 NEC

250.122(D) Motor Circuits. Where the overcurrent device consists of an instantaneous trip circuit breaker or a motor short-circuit protector, as allowed in 430.52, the equipment grounding conductor size shall be permitted to be based on the rating of the motor overload protective device but not less than the size shown in Table 250.122.

Other than that your stuck with increasing the EGC

 

[don_resqcapt19]

Example a 208 volt 2 hp single phase motor minimum circuit would be 16.5 so provide 12 AWG conductors but will not start and run on 20 amp over current device so increase to 30 amp inverse time circuit breaker does the EGC have to rate on the 30 amp breaker.

While the rule says to use Table 250.122 and this would require a #10 EGC, you are not ever required to have an EGC larger than the circuit conductors. In this case the #12 EGC is code complaint for the 30 amp OCPD.

250.122 Size of Equipment Grounding Conductors
(A) General Copper, aluminum, or copper-clad aluminum equipment grounding conductors of the wire type shall not be smaller than shown in Table 250.122 but shall not be required to be larger than the circuit conductors supplying the equipment. Where a raceway or a cable armor or sheath is used as the equipment grounding conductor, as provided in 250.118 and 250.134(A), it shall comply with 250.4(A)(5) or (B)(4).

Don