What size maximum level of primary-only overcurrent


1 With the exception of class 2 or class 3 transformers, if the disconnecting means for a transformer is not in sight of the transformer, the disconnecting means is required to be

A. lockable.

B. moisture resistant.

C. weatherproof.

D. bonded.

2. Which of the following should not be connected to the life safety branch circuit within a health care facility?

A. Nurse call system

B. Elevator

C. Stairway lighting

D. Alarm system

3. Two electricians are discussing transformer installations. Electrician A says that there is no size requirement for the door sill of a transformer vault as long as the sill would contain the oil from the largest transformer. Electrician B says that the AHJ can require fire rating of three hours for vault doors on an exterior wall. Which of the following statements is correct?

A. Only Electrician B is correct.

B. Only Electrician A is correct.

C. Neither electrician is correct.

A. 17.5 A

B. 13.5 A

C. 20 A

D. 15 A

9. What hazardous location designation applies to facilities where flammable gases are handled, processed or used, but under normal circumstances there is not a threat of explosion?

A. Class I, Division 1

B. Class I, Division 2

C. Class II, Division 2

D. Class II, Division 1

10. A parking garage used only for vehicle parking or storage would have what classification according to the NEC?

A. Unclassified

B. Class I, Division 2

C. Class III

D. Class I, Division I

11. According to the NEC, service equipment at a carnival can't be installed in a location accessible to unqualified persons unless the equipment is

A. grounded.

B. lockable.

C. bonded.

D. weatherproof.

12. Which of the following is not a general provision requirement for transformers per the NEC?

A. Temperature class marking for oil-insulated transformers

B. Primary and secondary voltage rating on nameplate

C. Lockable disconnecting means for remote locations

D. Ventilation that prevents temperature rise in excess of the transformer rating

13. According to the NEC, conduit seals are required within _______ inches from a pressurized enclosure when the conduit is not pressurized in Class I, Division 1 protection systems.

A. 12

B. 30

C. 18

D. 24

14. What is the maximum size fuse that may be used to protect a 60 kVA, nonsupervised transformer having a 4,160 V primary and 5% impedance?

A. 35 A

B. 25 A

C. 30 A

D. 20 A

15. To be in compliance with the NEC, transformer vaults must have a fire-resistance rating of _______ hours and concrete floors that are at least _______ inches thick, unless protected by automatic sprinkler systems.

A. 4, 4

B. 2, 3

C. 1, 3

D. 3, 4

16. In Class II, Division 2, conditions fuses, switches, circuit breakers, and similar devices must be installed in enclosures that are

A. vapor proof.

B. watertight.

C. airtight.

D. dust tight.

17. A hazardous location in which flammable gases or vapors exist in sufficient quantities to cause an explosion, as defined by the NEC?

A. Class II

B. Class I

C. Unclassified

D. Class III

18. Two electricians are discussing hazardous locations. Electrician A says that a motor installed in a Class II, Division 2 can be totally enclosed and fan cooled. Electrician B says that the installation requirements for motor controllers in a Class 3 location can be more relaxed than for a Class I location. Which of the following statements is correct?

A. Only Electrician A is correct.

B. Both electricians are correct.

C. Neither electrician is correct.

D. Only Electrician B is correct.

19. What size maximum level of primary-only overcurrent protection is required for a 600-volt transformer with a primary current rating of 54 amperes?

A. 50

B. 60

C. 100

D. 70

20. According to the NEC, which of the following protection techniques is permitted for Class I, Division 1 or 2 Locations?

A. Hermetically sealed equipment

B. Dust-tight equipment

C. Nonincendive equipment

D. Explosion-proof equipment.

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