Posted: February 25th, 2021

Exam: 006830rr – transformers and special locations

Exam: 006830RR – Transformers and Special Locations


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. weatherproof.

C. moisture resistant.

D. bonded.


2. Two electricians are discussing guarding requirements for transformers. Electrician A says that a warning sign indicating the operating voltage of live parts on a transformer is required if the live parts are exposed. Electrician B says that dry-type transformers can be installed without an enclosure. Which of the following statements is correct?

A. Neither electrician is correct.

B. Both electricians are correct.

C. Only Electrician A is correct.

D. Only Electrician B is correct.


3. Which of the following is a NEC violation for wiring installed in a place of assembly?

A. Permanent wiring using AC cable containing an insulated EGC

B. Permanent wiring in nonmetallic raceway encased by one inch of concrete

C. Temporary wiring laid directly on the floor

D. Temporary wiring not protected by GFCIs


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

A. vapor proof.

B. airtight.

C. dust tight.

D. watertight.


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

A. Class I

B. Unclassified

C. Class III

D. Class II


6. Two electricians are discussing hazardous locations. Electrician A says that hazardous location classifications are determined by the presence of gases, dust, or ignitable fibers. Electrician B says that division 2 conditions would not create a fire or explosion under normal circumstances. Which of the following statements is correct?

A. Both electricians are correct.

B. Neither electrician is correct.

C. Only Electrician A is correct.

D. Only Electrician B is correct.






7. Two electricians are discussing special requirements for health care facilities. Electrician A says that a nursing home is required to include an emergency system circuit. Electrician B says that GFCI outlets are not required in the bathroom area of some critical-care patient rooms. Which of the following statements is correct?

A. Both electricians are correct.

B. Neither electrician is correct.

C. Only Electrician B is correct.

D. Only Electrician A is correct.


8. Ignoring any exceptions, which of the following transformer types is not required to be installed in a vault?

A. Dry-type, indoor, rated over 35 kV

B. Dry-type, indoor, rated 1121/2 kVA or less

C. Oil-insulated, installed indoors

D. Nonflammable fluid-insulated, insulated rated over 35 kV


9. 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. 24

B. 30

C. 12

D. 18


10. 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. 2, 3

B. 1, 3

C. 3, 4

D. 4, 4


11. 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 II, Division 2

B. Class I, Division 1

C. Class I, Division 2

D. Class II, Division 1


12. What size primary fuse is required to protect a 5 kVA, 208 V, 3Φ transformer?

A. 17.5 A

B. 13.5 A

C. 15 A

D. 20 A


13. Two electricians are discussing transformers. Electrician A says that to insure proper ventilation, the required clearances can be found on the transformer nameplate markings. Electrician B says that exposed live parts on a transformer require the installation of a sign that indicates the operating voltage. Which of the following statements is correct?

A. Only Electrician A is correct.

B. Only Electrician B is correct.

C. Both electricians are correct.

D. Neither electrician is correct.


14. What article in the NEC would you reference to determine the wiring requirements for a local dinner theater?

A. Article 520

B. Article 525

C. Article 522

D. Article 530


15. Lighting fixtures used in Class III, Division 1 and Division 2 locations are required to be marked with the maximum lamp wattage that can be used without exceeding a fixture surface temperature of _______° F.

A. 165

B. 329

C. 453

D. 250


16. What is the T Code for equipment having a maximum surface temperature of 392°F?

A. T4

B. T3A

C. T3

D. T4A


17. 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. 70

B. 60

C. 100

D. 50


18. All 15 A and 20 A, 125 V receptacles installed in a pediatric playroom in a health care facility must be _______ receptacles.


B. tamper-resistant

C. nongrounding

D. standard


19. 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. 20 A

C. 30 A

D. 25 A


20. Which of the following is not a consideration when installing a LFLI transformer indoors?

A. Pressure relief vent

B. Automatic fire extinguishing system

C. Voltage rating

D. Building type



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