feeding two 20A motors from one 30A breaker?

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malachi constant

Senior Member
Location
Minneapolis
Gymnasiums equipment provider supplied controls that take a 30A/1P input and control up to four relays. Backstop motors are 11.5 FLA. We would like to run #12s from motor to relay, and run two of these off the 30A breaker with #10s between breaker and relay controls. [With breaker sized at (125% x 11.5A) + 11.5A = 25.9A, have to round up to 30A breaker.]

Is it OK to protect the pair of 11.5A motors and associated #12 wires using the single 30A/1P breaker? I believe so because overload protection for the motors should be located at the motors (so #12s are OK), and per 430.52 we can go up to 250% of motor FLA (which is 11.5A x 250% = 28.75A, and per exception #1 you can round up - so 30A breaker is OK).

I think we are good here but seems like every time I ask about this kind of situation I learn another wrinkle. Your thoughts are appreciated!
 
Sounds fine at 25.9 amps your minimum conductor size is as you've stated #10, you quoted 430.52 which is for individual motor circuits. Take a look at 430.53.
[h=3][/h].
 
...You quoted 430.52 which is for individual motor circuits. Take a look at 430.53.[h=3][/h].

Thank you for pointing me to this - 430.53 definitely is where I should be looking. Walking through it here:
430.53 says you can put multiple motors on one circuit provided you meet (D) -AND- a one of (A) (B) or (C).
* We meet (B) as it requires the branch circuit/short circuit/ground fault protective device for the smallest motor to to not exceed that allowed by 430.52. Per the OP 30A is allowed to feed an 11.5 FLA motor. So we are good on this and therefore good on the [A B or C] point.
* We meet all the conditions spelled out in (D).
So we're good. Thanks!
 
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