Motor Question

[Kaito]

Studying to take my Admin and am confused on why they didn’t take into consideration of the service factor.

There are three motors; one 5hp, 230v, single-phase motor with a service factor of 1.20; and two 1^1/2hp, 120v, three-phase motors. Using an inverse time breaker, the 3-wire feeder conductor protective device after balancing all three motors will be ____.
(a) 60A
(b) 70A
(c) 80A
(d) 90A

The answer is D

 

[ptonsparky]

…Two 1 1/2 hp, 120 v, three-phase motors…

I hadn’t heard of 120 volt three phase motors. Do you have a typo?

 

[Kaito]

Typo, two 1^1/2 hp, single phase motors*

 

[kwired]

only thing service factor typically does is make you use different motor overload setting if it is only 1.0 vs 1.15 or 1.25.

SCGFprotection is not impacted by service factor.

 

[augie47]

For SCGF protection you use the Tables.40.52 and 430.248 do not address service factor the way 430 Part III (overload) does,

 

[Jraef]

only thing service factor typically does is make you use different motor overload setting if it is only 1.0 vs 1.15 or 1.25.

SCGFprotection is not impacted by service factor.

Red herring thrown in to confuse you.