NEC 430 Motor Control

Conductors supplying several motors shall not be sized smaller than _____ percent of the full-load current rating of the highest rated motor, plus the sum of the full-load current ratings of all other motors in the group, plus the ampacity of other loads. 80% 100% 125% 150%

125%

Motors shall be located so that adequate _____ is provided and so that maintenance, such as lubrication of bearings and replacing of brushes, can be readily accomplished. space ventilation protection all of these

Ventilation

If a motor disconnecting means is a motor-circuit switch, it shall be rated in _____. horsepower watts amperes locked-rotor current

Horsepower

T or F A branch-circuit overcurrent device can serve as the disconnecting means for a stationary motor of 1/8 hp or less.

True

T or F Circuit conductors on the output of an adjustable-speed drive system are susceptible to breakdown under certain conditions due to the characteristics of the output waveform of the drive.

True

T or F Motor control circuits shall be arranged so they will be disconnected from all sources of supply when the disconnecting means is in the open position.

True

T or F Where more than one motor disconnecting means is provided in the same motor branch circuit, at least one of the disconnecting means shall be readily accessible.

True

Overload devices are intended to protect motors, motor control apparatus, and motor branch-circuit conductors against _____. excessive heating due to motor overloads excessive heating due to failure to start short circuits and ground faults excessive heating due to motor overloads and excessive heating due to failure to start

excessive heating due to motor overloads and excessive heating due to failure to start

In determining the highest rated motor for purposes of complying with 430.24, 430.53(B), and 430.53(C), the highest rated motor shall be based on the rated full-load current as selected _____. from the motor nameplate from Tables 430.247, 430.248, 430.249, and 430.250 by multiplying the horsepower by 746 watts using the largest horsepower motor

from Tables 430.247, 430.248, 430.249, and 430.250

A separate overload device used to protect continuous-duty motors rated more than 1 hp shall be selected to trip at no more than _____ percent of the motor nameplate full-load current rating if marked with a service factor of 1.15 or greater. 110 115 120 125

125

The maximum dual-element time-delay fuse branch circuit protection for a single-phase motor is _____ percent of the appropriate current rating found in Table 430.248. 125 150 175 225

175

The maximum rating or setting of an inverse time breaker used as the motor branch-circuit short-circuit and ground-fault protective device for a single-phase motor is _____ percent of the full-load current given in Table 430.248. 125 175 250 300

250

Motor control circuit conductors that extend beyond the motor control equipment enclosure shall have short-circuit and ground-fault protection sized not greater than _____ percent of the value specified in Table 310.16 for 60°C conductors. 100 150 300 400

300

Overcurrent protection for motor control circuits shall not exceed _____ percent if the conductor is based on Table 310.17 and does not extend beyond the motor control equipment enclosure. 100 150 300 400

400

For stationary motors of 2 hp or less and 300V or less on ac circuits, the controller can be an ac-rated only general-use snap switch where the motor full-load current rating is not more than _____ percent of the rating of the switch. 50 60 70 80

80

The maximum instantaneous trip breaker branch circuit protection for a single-phase motor is _____ percent of the appropriate current rating found in Table 430.52. 175 225 300 800

800

Part IV of Article 430 specifies devices intended to protect _____ against overcurrent due to short circuits or ground faults. motor branch-circuit conductors motor control apparatus motors all of these

All of These

A motor can be provided with combined overcurrent protection using a single protective device to provide branch-circuit _____ protection where the rating of the device provides the overload protection specified in 430.32. short-circuit ground-fault motor overload all of these

All of these

A motor disconnecting means can be a listed _____. molded case circuit breaker motor-circuit switch rated in horsepower molded case switch any of these

any of these

Circuit conductors on the output of an adjustable-speed drive system are susceptible to breakdown under certain conditions. Factors affecting the conductors include but are not limited to the output _____. voltage frequency current any of these

any of these

A _____ rated in amperes shall be permitted as a controller for all motors. branch-circuit inverse time circuit breaker or molded case switch dual-element time-delay fuse snap switch GFCI protected device

branch-circuit inverse time circuit breaker or molded case switch

The motor _____ currents listed in Tables 430.247 through 430.250 shall be used to determine the ampacity of motor circuit conductors and short-circuit and ground-fault protection devices. nameplate full-load power factor service factor

full-load

An individual disconnecting means shall be provided for each motor controller and be located _____ from the controller location. in sight within 3 ft within 10 ft within 25 ft

in sight

T or F Conductors supplying several motors, or a motor(s) and other load(s), shall have an ampacity not less than the sum of 125 percent of the full-load current rating of the highest rated motor plus the sum of the full-load current ratings of all the other motors in the group and 100 percent of the remaining noncontinuous and continuous nonmotor loads.

False

For general motor applications, the motor branch-circuit short-circuit and ground-fault protection device shall be sized based on the _____ values. motor nameplate NEMA standard NEC Table Factory Mutual

NEC Table

T or F Where the motor short-circuit and ground-fault protection devices determined by Table 430.52 do not correspond to the standard sizes or ratings, a higher rating that does not exceed the next higher standard ampere rating shall be permitted.

True

Each motor used in a continuous duty application and rated more than 1 hp shall be protected against overload by a separate overload device that is responsive to motor current. The overload device for motors with a marked temperature rise 40°C or less, shall be rated at no more than _____ percent of the motor nameplate full-load current rating. 80 115 125 175

125