Question

(12 If a conductor is covered, it is: A) Encased with an insulation recognized by the Code 8) Encased with an outer covering not recognized as electrical insulation C) Effectively isolated from ground faults D) Covered with a material of a composition and thickness recognized by UL (13 Open motors with commutators shall material, but this: A) Is only required for over 600 volts B) Does not prohibit these motors from a Class I location C) Shall not prohibit these motors on wooden floors D) None of these be located so sparks cannot reach adjacent combustible (14 The branch-circui t conductors supplying a motor that draws 40 amperes must have an ampacity not less than D) 70 amperes A) 40 amperes C) 60 amperes B) 50 amperes (15 If n o other information is given, a continuous-duty motor that draws 100 amperes must be protected by an overload device rated at not more than: A) 125 amperes C) 140 amperes D) 115 amperes B) 150 amperes (16 The branch- circuit overcurrent device may serve as the disconnecting means for motor-driven appliances rated not over: A) 1/2 horsepower B) 1 horsepower C) 3/4 horsepower D) 1/8 horsepower (17 A power factor correction capacitor connected on the load side of the overload device of a motor reduces the line current by 20%, if the full-load current of the motor is 100 amperes, the setting of an overload device in the circuit is based on a current of A) 100 amperes D) 150 amperes C) 80 amperes B) 125 amperes (18 Conductors supplying two or more motors must have an ampacity equal to the sum of the full-load current rating of all the motors plus what percent of the highest rated motor in the group: A) 25% C) 75% D) 100% B) 50% (19 What may the locked-rotor current be assumed to be for small motor-compressors not having the locked-rotor current marked on the nameplate? A) 2 times the rated load current C) 6 times the rated load current D) 8 times the rated load current B) 4 times the rated load current (20 What is the maximum overcurrent protective device allowed on a 480-volt branch circuit with several small motors connected - all of which are under 1 horsepower and the maximum load of each motor is 5 amperes A) 10 amperes D) 30 amperes B) 15 amperes C) 20 amperes

Answer 1

12). B.

Covered is not same as Insulated. If a conductor is covered, it is covered in the material of composition or thickness not recognised by codes as Electrcial Insulation. If a conductor is insulated, it is encased with the material of composition or thickness recognised by the codes as electrcial insulation.

13). C
Installation of these open motors with commutators is permitted on the wooden floors.

14). B.

Per the specification, the branch circuit conductors supplying a motor that draws 40 A must have an ampacity of not less than 125 % of the motor marked rating i.e, 40x 1.25 = 50 A

15). A.
The overload device should be rated atmost 125 percent of the continuous duty motor rating.  i.e, 125 Amperes in the above case.Though, such overload protection is not required for the motors having capacity less than 1 Hp.

16). D.
This is a electrical specification to be followed.

17). After power factor correction capacitor the line current gets reduced to 80 Amp. Now, as per the codes the overload protection device should not be more than 125 percent of the motor rating. Following this the overload device is based on the current equal to 80x 1.25 = 100 Amperes.

18). None Answer is 125% based on NEC Codes.
Conductors supplying more than two or more motors must have an ampacity not less than 125% of the rating of the highest rated motor plus the sum of full load current of all the other motors.

19). C.
General Rule

20). B.
This is by NEC Codes.

Several motors, each not exceeding 1 horsepower, are permitted on a branch circuit protected at not more than 20 amperes at 120 volts or less, or at 600 volts or less protected at not over 15 amperes if all of the following conditions can be met:

The rating of the branch-circuit short-circuit and ground-fault protective device marked on the controllers is not exceeded.
The full-load rating of each motor does not exceed 6 amperes.
Individual overload protection conforms with section 430-32 of the NEC