1. For a 1½ horsepower motor that is 11” in diameter, the usable volume of the terminal housing for wire to wire connections may be no smaller than ______ cubic inches.
a) 10.5
b) 16.8
c) 17.0
d) 22.4
2. For a part-winding connected motor, the ampacity of the branch-circuit conductors on the line side of the controller must not be less than 125 percent of the motor full-load current as determined by appropriate code tables. The ampacity of the conductors between the controller and the motor shall not be less than ______ percent of the motor full-load current rating as determined by appropriate code tables.
a) 50
b) 58.2
c) 62.5
d) 70
3. When selecting a separate overload device that is responsive to motor current, this device must be selected to trip or be rated at 125% percent based on the motor is ______ on which condition(s)?
a) marked temperature rise 40°C or more – 125%
b) marked service factor 1.15 or more – 125%.
c) Answers (a) & (b) are correct
d) None of the above
4. Where the rating specified in Table 430.52(C)(1), is not sufficient for the starting current of the motor which has a FLA rating of 112 amperes, the rating of an inverse time circuit breaker can be increased a maximum of ______ percent.
a) 250
b) 300
c) 400
d) 450
5. If a drawbridge motor has a duty cycle of 30 minutes, with a full load ampere value 124 amperes at 460 volts, what must the minimum circuit ampacity of the supply conductors to this motor be?
a) 155
b) 179.8
c) 111.6
d) 124
6. Motors with 50- and 60-Hz ratings shall be marked with a code letter designating the locked-rotor kilovolt-ampere (kVA) per horsepower (hp) based on ______
a) 50 Hz
b) 60 Hz
c) 50/60Hz
d) Any of the above
7. A 460 volt, 150 HP wound rotor grinder motor employs a heavy starting duty resistor classification. The secondary resistor is separate from the control. If maximum resistor grid- secondary current would be the 950 amperes, what is the minimum circuit ampacity for the conductors connecting the rotor output to the resistor grid?
a) 807.5
b) 522.5
c) 427.5
d) 475
8. Which statement(s) regarding instantaneous trip circuit breakers is(are) not true?
a) An instantaneous, nonadjustable - trip breaker may be used for BC, SC & GF protection of motor circuits.
b) Instantaneous-trip circuit breakers shall be adjustable and part of a listed combination motor controller.
c) They shall have coordinated motor overload and short-circuit and ground-fault protection in each conductor.
d) None are true statements.
9. When considering protection based on 430.52 for motors, what requirement does the NEC make for torque motors?
a) Torque motor branch circuits must be protected at the motor nameplate current rating.
b) Torque motor FLA based on code tables must be used for BC, SC, an GF’s.
c) Torque motors shall be protected based on manufacture’s required instructions.
d) Torque motors may be protected up to 150& of their FLA based on 430.52.
10. What’s the rule for sizing BC, SC, & GF protective devices for multimotor and combination load equipment?
a) The protection shall be sized based on 125% of the largest motor plus the some of all other motors in the group based on their code book FLA
b) The combination -load equipment protection shall not exceed the rating marked on the equipment in accordance with 430.7(D).
c) Supply conductor temperature shall be based on the largest load served as part of the group
d) All of the above
ANSWERS
1. (b) 16.8 [Table 430.12(B)]
2. (c) 62.5 [430.22(D)]
3. (c) Answers (a) & (b) are correct [430.32(A)(1)]
4. (b) 300 [430.52(C)(1)(b)(3)]
5. (c) 111.6 [430.22(E)]
6. (b) 60 Hz [430.7(B)(4)]
7. (c) 427.5 [Table 430.23(C)]
8. (a) An instantaneous, nonadjustable - trip breaker may be used for BC, SC & GF protection of motor circuits. [430.52(C)(3)(a)]
9. (a) Torque motor branch circuits must be protected at the motor nameplate current rating. [430.52(D)]
10. (b) The combination -load equipment protection shall not exceed the rating marked on the equipment in accordance with 430.7(D). [430.54]