Lesson 4: The Requirements For Electrical Installations In Class II Hazardous (Classified) Locations

Question 1

Explosionproof equipment and wiring shall not be required and shall not be acceptable in Class II locations unless also identified for such locations.

a. True
b. False

NEC REF:

Answer 1

a. True

502.5

Question 2

Which of the following wiring methods is permitted to be used in Class II, Division 1 locations?

I. Threaded rigid metal conduit
II. Threaded steel intermediate metal conduit
III. Type MI cable
IV. Type MC-KL cable

a. I. and II.
b. I., II., and III.
c. I., II., and IV.
d. None of the above

NEC REF:

Answer 2

b. I., II., and III.

502.10(A)(1)

Question 3

Identified elevator cable Type EO, Type ETP, or Type ETT, shown under the “use” column in Table 400.4 for “Hazardous (Classified) Locations,” is permitted for flexible connections to elevators in Class II, Division 1 locations where it is terminated with ______.

a. fittings approved for the location
b. listed dusttight fittings
c. listed explosionproof fittings
d. none of the above

NEC REF:

Answer 3

b. listed dusttight fittings

502.10(A)(2)(6)

Note: The NEC uses the word “or” to address the three cable types to make it clear that all of them do not have to be used, but it should be understood that it does not prevent all three from being used in the same Class II, Division 1 location.

Question 4

Boxes and fittings installed in Class II, Division 1 locations shall be provided with threaded bosses for connection to conduit or cable terminations and shall be ______.

a. dust ignitionproof
b. dusttight
c. labeled
d. listed for the location

NEC REF:

Answer 4

b. dusttight

502.10(A)(3)

Question 5

Type TC-ER cable installed in a Class II, Division 2 location shall include a bonding jumper in addition to any drain wire that may be present.

a. True
b. False

NEC REF:

Answer 5

b. False

502.10(B)(1)(4)

Note: NEC 502.10(B)(1)(4) requires Type TC-ER cable to include an equipment grounding conductor.

Question 6

Nonincendive field wiring shall be permitted using any of the wiring methods permitted for ______ locations.

a. Class II, Division 1
b. Class II, Division 2
c. unclassified
d. none of the above

NEC REF:

Answer 6

c. unclassified

502.10(B)(3)

Question 7

When Type P cable is installed in ladder, ventilated trough, or ventilated channel cable trays, the cables shall be installed in a single layer, with a space ______ the larger cable diameter between the two adjacent cables, unless otherwise protected against dust buildup resulting in increased heat.

a. equal to
b. not less than
c. three times
d. two times

NEC REF:

Answer 7

b. not less than

502.10(A)(1)(7)

Question 8

A vertical raceway not less than ______ long, that extends downward from a dust-ignitionproof enclosure, is a permitted method of raceway sealing in Class II locations.

a. 2’
b. 2 m
c. 5’
d. 10’

NEC REF:

Answer 8

c. 5’

502.15(3)

Question 9

Surge-protective capacitors shall be of a type ______ for specific duty.

a. approved
b. designed
c. identified
d. listed

NEC REF:

Answer 9

b. designed

502.35

Question 10

Where transformers and/or capacitors containing liquids that will burn are installed in a vault, doors that communicate with the Class II, Division 1 location are required to have carefully fitted, self-closing fire doors on both sides of the wall that are provided with ______ to minimize entrance of dust into the vault.

a. fire dampers in any vents
b. locks
c. suitable seals
d. none of the above

NEC REF:

Answer 10

c. suitable seals

502.100(A)(1)(1)

Question 11

Transformers and capacitors that do not contain a liquid that will burn shall be installed in vaults complying with 450.41 through 450.48 or be ______ as a complete assembly, including terminal connections.

a. approved
b. identified
c. listed
d. suitable

NEC REF:

Answer 11

b. identified

502.100(A)(2)

Question 12

Transformers and capacitors are permitted to be installed in a Class II, Division 1, Group E location if they are enclosed in a vault.

a. True
b. False

NEC REF:

Answer 12

b. False

502.100(A)(3)

Question 13

Switches, circuit breakers, motor controllers, fuses, push buttons, relays, and similar devices in Class II, Division 1 locations shall be provided with enclosures ______ for the location.

a. approved
b. listed
c. suitable
d. none of the above

NEC REF:

Answer 13

d. none of the above

502.115(A)

Question 14

Motors, generators, and other rotating electrical machinery in Class II, Division 1 locations shall be ______.

a. approved for the location
b. identified for the location
c. totally enclosed pipe-ventilated
d. b. or c.

NEC REF:

Answer 14

d. b. or c.

502.125(A)

Question 15

Ventilating pipes for motors, generators, or other rotating electrical machinery, or for enclosures for electrical equipment, installed in Class II, Division 1 locations, shall be of metal not less than ______ in thickness or of equally substantial noncombustible material.

a. 0.015”
b. 0.021”
c. 0.025”
d. 0.052”

NEC REF:

Answer 15

b. 0.021”

502.128

Question 16

Where wiring between an outlet box or fitting and a pendant luminaire is installed in a Class II, Division 1 location and the wiring is not enclosed in conduit, flexible cord ______ shall be permitted to be used in accordance with 502.10(A)(2)(5).

a. approved for the location
b. listed for extra-hard usage
c. listed for hard usage
d. listed for Hazardous (Classified) Locations

NEC REF:

Answer 16

c. listed for hard usage

502.130(A)(3)

Question 17

Each luminaire installed in a Class II, Division 1 location shall be identified for the location and shall be clearly marked to indicate the type and _____ of the lamp for which it is designed.

a. maximum temperature
b. maximum wattage
c. voltage
d. wattage range

NEC REF:

Answer 17

b. maximum wattage

502.130(A)(1)

Question 18

In Class II, Division 1 locations, ventilating pipes, including their connections to motors or to the dust-ignitionproof enclosures for other equipment, shall ______ throughout their length.

a. be dust-ignitionproof
b. be dusttight
c. be sealed
d. have labels

NEC REF:

Answer 18

b. be dusttight

502.128(A)

Question 19

Transformers that are rated in excess of 25 kVA and contain askarel that are installed in a Class II, Division 2 location shall have a minimum airspace of ______ between the transformer cases and any adjacent combustible material.

a. 6”
b. 12”
c. 18”
d. 24”

NEC REF:

Answer 19

a. 6”

502.100(B)(2)(3)

Question 20

Switching mechanisms associated with control transformers, solenoids, impedance coils, and resistors that are installed in Class II, Division 2 locations shall be provided with enclosures that are ______, where they are installed in Class II, Division 2 locations.

a. dust-ignitionproof
b. dusttight
c. identified for the location
d. a. or c.
e. b. or c.

NEC REF:

Answer 20

e. b. or c.

502.120(B)(1)

Question 21

In Class II, Division 2 locations, motors, generators, and other rotating electrical equipment shall have a maximum full-load external temperature in accordance with 500.8(D)(2) for ______ when operating in free air (not dust blanketed).

a. abnormal operation
b. continuous duty
c. full loads
d. normal operation

NEC REF:

Answer 21

d. normal operation

502.125(B)

Question 22

In Class II, Division 2 locations, enclosures for fuses, switches, circuit breakers, and motor controllers, including push buttons, relays, and similar devices, shall be ______ or otherwise identified for the location.

a. approved
b. dust-ignitionproof
c. dusttight
d. suitable

NEC REF:

Answer 22

c. dusttight

502.115(B)

Question 23

In Class II, Division 2 locations, ventilating pipes and their connections shall be sufficiently tight to prevent the entrance of ______ quantities of dust into the ventilated equipment or enclosure and to prevent the escape of sparks, flame, or burning material that might ignite dust accumulations or combustible material in the vicinity.

a. appreciable
b. dangerous
c. large
d. moderate

NEC REF:

Answer 23

a. appreciable

502.128(B)

Question 24

Flexible cords are permitted to be used in Class II locations for electric submersible pumps that have means for removal without entering the wet-pit.

a. True
b. False

NEC REF:

Answer 24

a. True

502.140(A)(3)

Question 25

Flexible cord used in Class II locations shall be supported by clamps or other ______ means to prevent tension on the terminal connections. a. approved b. identified c. suitable d. none of the above NEC REF:

Answer 25

c. suitable 502.140(B)(3)

Question 26

Article 500 covers area classification and general requirements for electrical and electronic equipment and wiring rated at all voltages where fire or explosion hazards might exist due to flammable gases, flammable liquid-produced vapors, combustible liquid-produced vapors, combustible dusts, combustible fibers/flyings, or ignitable fibers/flyings in Class I, Division 1 or Class I, Division 2 hazardous (classified) locations, Class II, Division 1 or Class II, Division 2 hazardous (classified) locations, and Class III, Division 1 or Class III, Division 2 hazardous (classified) locations. Atmospheres containing combustible metal dusts, including aluminum, magnesium, and their commercial alloys, or other combustible dusts whose particle size, abrasiveness, and conductivity present similar hazards in the use of electrical equipment are grouped as Class II Combustible Dust Group ? in Article 500. A. C B. E C. F D. G

Answer 26

B. E Note: See NEC 500.6(B)(1).

Question 27

Contacts for signaling, alarm, remote-control, and communications systems and for meters, instruments, and relays in Class II, Division 2 location shall comply with the requirements of 502.150(A)(1) or be installed in enclosures that are ______. a. dusttight b. identified for the location c. listed d. a. or b. NEC REF:

Answer 27

d. a. or b. 502.150(B)(1)(a)