Motor Circuit Calculations -3 (NEC Code Questions)

Question 1: In no-case the rating of a shot circuit ground fault protective device for single motor compressor should not exceed ................ percent of the motor compressor rating?

• 175
• 225
• 200
• 150

NEC Reference: NEC 440.22(A)

Question 2: What is the minimum ampere rating of short circuit ground fault protective device that can be used for industrial motor compressor?

• 10 A
• 15 A
• 20 A
• 25 A

NEC Reference: NEC 440.22(A)

Question 3: Which of the following size conductor is required for a 18 A motor compressor connected to 240 V circuit at 75 ⁰C?

• 12 AWG
• 10 AWG
• 14 AWG
• 8 AWG

NEC Reference: NEC 22.5

Question 4: Which size branch circuit protection is required for 20A motor compressor connected to 240 Volts circuit?

• 40 A
• 35 A
• 45 A
• 50 A

NEC Reference: NEC 440.22(A)

Question 5: What size branch conductor is suitable for 5 HP, 208 V three phase motor?

• 12 AWG
• 10 AWG
• 8 AWG
• 14 AWG

NEC Reference: NEC 16.7

Question 6: The single pole switches can be used to control the motors when those are rated at ................... hp or less.

• 1/2
• 1/4
• 3/4
• 1

Question 7: The branch circuit over current device of the stationary motor which are rated less than ........... may serve as the controller of motor.

• 5 hp
• 3 hp
• 1 hp
• 1/8 hp

NEC Reference: NEC 430.81(A)

Question 8: A 2400 volts motor disconnecting means must be capable of being of being locked in the ......................

• closed position
• open position
• on position
• both open and close position

Question 9: The overload protection must be provided for the motor if it is rated more than ......... hp

• 1/8
• 1/4
• 1/2
• 1

NEC Reference: NEC 430.32(A)

Question 10: A disconnecting means should be located in sight from a motor not more than ............... distance.

• 25 feet
• 50 feet
• 70 feet
• 90 feet