PC Motors and Motor Controls 2

Question 1

What is the minimum horsepower rating required for a motor disconnecting means per NEC 430.110?

Accepted Answer

Equal to the motor's HP rating

Answer

NEC 430.110(A) requires the motor disconnect to have an HP rating at least equal to the motor's HP rating at the applied voltage.

Question 2

Per NEC 430.102, where must the motor disconnecting means be located?

Accepted Answer

Within sight of the motor and within 50 feet

Answer

NEC 430.102(B) requires the motor disconnect to be within sight of the motor, meaning visible and not more than 50 feet away.

Question 3

What type of motor starting method is used to reduce inrush current during startup?

Accepted Answer

Reduced voltage starting

Answer

Reduced voltage starters (autotransformer, wye-delta, or electronic soft starters) limit inrush current by applying less than full voltage during starting.

Question 4

What is the standard secondary voltage for a motor control circuit transformer per NEC 430.72?

Accepted Answer

120V

Answer

NEC 430.72 permits control circuit conductors supplied by a grounded transformer secondary at up to 120V without additional overcurrent protection in many cases.

Question 5

A squirrel cage induction motor is classified as what type of motor?

Accepted Answer

AC induction motor

Answer

A squirrel cage induction motor is the most common AC induction motor, named for its rotor conductor arrangement that resembles a squirrel cage.

(PC) Professional Electrical Contractor Practice Test

(PC) Professional Electrical Contractor Practice Test

PC Motors and Motor Controls 2