4A2 - Motors Level 2 - Lesson 6: Motor Branch Circuits

Match the motor conductor ampacity to the correct THWN (75°C) copper wire size using Table 310.15(B)(16).

10 6 4 4/0

A single 100-horsepower, 440-volt, 3-phase, continuous-duty, induction type Design B motor is supplied by a motor branch circuit. Calculate the minimum ampacity for the motor branch-circuit conductors.

155 A

A single 3-horsepower, 240-volt, single-phase, continuous-duty, induction type Design B motor is supplied by a motor branch circuit. Calculate the minimum ampacity for the motor branch-circuit conductors.

21.25 A

A 60-horsepower, 208-volt, 3-phase, squirrel-cage motor is supplied by a motor branch circuit. Calculate the minimum ampacity for the motor branch-circuit conductors.

211.25 A

One 10-horsepower, 208-volt, 3-phase, continuous-duty, induction type Design B motor; one 25-horsepower, 208-volt, 3-phase, continuous-duty, induction type Design B motor; and one 30-horsepower, 208-volt, 3-phase, continuous-duty, induction type Design B motor are supplied by a single motor branch circuit. Calculate the minimum ampacity for the single motor branch-circuit conductors supplying all three motors.

215.6 A

A single 75-horsepower, 208-volt, 3-phase, continuous-duty, induction type Design B motor is supplied by a motor branch circuit. Calculate the minimum ampacity for the motor branch-circuit conductors.

263.75 A

Match the motor conductor ampacity to the correct THWN (75°C) copper wire size using Table 310.15(B)(16).

3 2 1 4/0

Using NEC Part XIV of Article 430, match the following motor data to the correct full-load current.

5.4 28 7.6 48.3

A single 30-horsepower, 460-volt, 3-phase, continuous-duty, induction type Design B motor is supplied by a motor branch circuit. Calculate the minimum ampacity for the motor branch-circuit conductors.

50 A

Three single-phase motors, rated 1/2 horsepower, 3/4 horsepower, and 2 horsepower, are to be installed on the same 120-volt branch circuit. Calculate the minimum ampacity of the branch-circuit conductors.

53.6 A

A 25-horsepower, 3-phase compressor motor with a full-load rating of 42 amperes and a branch-circuit selection current of 45 amperes is installed on an individual 3-phase, 460-volt branch circuit. Calculate the minimum ampacity for the single refrigeration branch-circuit conductors.

56.25 A

A 10-horsepower, 208-volt, single-phase, continuous-duty, induction type Design B motor is supplied by a motor branch circuit. Calculate the minimum ampacity for the motor branch-circuit conductors.

68.75 A

A 7 1/2-horsepower, 220-volt, single-phase compressor motor with a full-load current rating of 38 amperes and a branch-circuit selection current of 42.5 amperes is installed with 5,000 watts of noncontinuous supplementary heat on a single-branch circuit. Calculate the minimum ampacity for the single refrigeration/heater branch-circuit conductors.

75.852 A

One branch circuit supplies a piece of fixed electric space heating equipment (motor-operated) with one 5-horsepower, 230-volt, single-phase motor and one unit of electric heat rated at 12,500 watts at 230 volts. Calculate the minimum branch-circuit ampacity to supply the combined load.

103 A

One branch circuit supplies two 15-horsepower, 240-volt, 3-phase compressor motors. Both motors can operate at the same time. Each motor has a full-load current of 43 amperes; and a branch-circuit selection current of 46 amperes. Calculate the minimum ampacity for the single refrigeration branch-circuit conductors.

103.5 A

One 3-horsepower, 240-volt, single-phase, continuous-duty, induction-type Design B motor; one 71/2-horsepower, 240-volt, single-phase, continuous-duty, induction-type Design B motor; and one 10-horsepower, 240-volt, single-phase, continuous-duty, induction-type Design B motor are supplied by a single motor branch circuit. Calculate the minimum ampacity for the single motor branch-circuit conductors supplying all three motors.

119.5 A

Match the motor conductor ampacity to the correct THWN (75°C) copper wire size using Table 310.15(B)(16).

12 8 2/0 300

Using NEC Part XIV of Article 430, match the following induction motor data to the correct full-load current.

13.6 11 57.5 62

A 230-volt, 3-phase, 25-horsepower squirrel-cage motor and a 230-volt, 30-horsepower synchronous motor are installed on the same motor branch circuit. What is the minimum ampacity of the conductors for this single branch circuit?

148 A

Two 10-horsepower, 440-volt, 3-phase, continuous-duty, induction type Design B motors are supplied by a single motor branch circuit. Calculate the minimum ampacity for the single motor branch-circuit conductors supplying both motors.

31.5 A

Match the conductor ampacity to the correct THWN (75°C) copper wire size using Table 310.15(B)(16).

6 4 4 2

Adjust the conductor ampacity, using Tables 310.15(B)(2)(a) and 310.15(B)(3)(a) as appropriate, and then match to the correct THWN (75°C) copper wire size using Table 310.15(B)(16).

6 2 1/0 1

One 15-horsepower, 440-volt, 3-phase, continuous-duty, induction type Design B motor and one 25-horsepower, 440-volt, 3-phase, continuous-duty, induction type Design B motor are supplied by a single motor branch circuit. Calculate the minimum ampacity for the single motor branch-circuit conductors supplying both motors.

63.5A

A single 10-horsepower, 240-volt, single-phase compressor motor with a rated load current of 50 amperes and a branch-circuit selection current (BCSC) of 54.5 amperes is supplied by a refrigeration equipment branch circuit. Calculate the minimum ampacity for the branch-circuit conductors.

68.13 A

One 2-horsepower, 120-volt, single-phase continuous-duty, induction type Design B motor and an additional noncontinuous load of 7,200 watts are supplied by a single branch circuit. Calculate the minimum branch-circuit ampacity to supply the motor load and the additional noncontinuous load.

90 A

Two individual motor branch circuits are installed in individual conduits for two 25-horsepower, 3-phase, 208-volt motors using THWN copper conductors. Calculate the minimum ampacity for each motor branch-circuit conductor.

93.5 A

A 60-horsepower, 3-phase, 440-volt motor is installed on an individual branch circuit. Calculate the minimum ampacity for the motor branch-circuit conductors.

96.25 A