Lesson 5: Requirements For Wiring In Class III Hazardous (Classified) Locations And Intrinsically Safe Systems Flashcards
Wiring methods permitted in Class III, Division 1 locations include ______.
I. AC cable
II. MC cable
III. RMC conduit
IV. RTRC conduit
a. I. and II.
b. I., II., and III.
c. I., III., and IV.
d. II., III., and IV.
NEC REF:
d. II., III., and IV.
503.10(A)(1)(1)
Where flexible connections are needed for flexibility in Class III, Division 1 locations, ______ are permitted to be used.
I. liquidtight flexible metal conduit installed with listed fittings
II. liquidtight flexible nonmetallic conduit installed with listed fittings
III. listed flexible connectors
IV. MC cable with a suitable polymeric jacket and installed with listed dusttight fittings
a. I., II., and III.
b. I., II., III., and IV.
c. I., II., and IV.
d. I., III., and IV.
NEC REF:
c. I., II., and IV.
503.10(A)(3)
Simple apparatus, not shown on the control drawing, is permitted in a nonincendive field wiring circuit, located in a Class III, Division 1 location, as long as the simple apparatus does not interconnect the nonincendive field wiring circuit to any other circuit.
a. True
b. False
NEC REF:
True
503.10(A)(4)
Type PLTC and Type PLTC-ER cable may be used in Class III, Division 2 locations for Class II and Class III circuits where the cable is terminated with ______ fittings. Type PLTC-ER cable must include an equipment grounding conductor in addition to any ______ that may be present.
a. dust ignitionproof / bonding jumper
b. dusttight / bonding jumper
c. listed / bonding jumper
d. listed / drain wire
NEC REF:
d. listed / drain wire
503.10(A)(1)(2)
Note: The answer to this question is found by looking at NEC 503.10(B) for the permitted wiring methods for Class III, Division 2 locations. This section states that the wiring methods for Class III, Division 2 locations are those found in 503.10(A). PLTC and PLTC-ER cables are listed in 503.10(A)(1)(2).
Wiring systems and equipment shall be grounded in accordance with ______ of Article 250, as applicable.
a. Parts I. and II.
b. Parts I. and IV.
c. Parts I., IV., and VI.
d. Parts I. and VI.
NEC REF:
d. Parts I. and VI.
503.30(A)
In sections, compartments, or areas that do not contain machinery and are used solely for storage, open wiring on insulators shall be permitted where installed in accordance with ______ of Article 398.
a. Part I.
b. Part II.
c. Part III.
d. Part IV.
NEC REF:
b. Part II.
503.10(B)(2)
Transformers, impedance coils, and resistors used as, or in conjunction with, control equipment for motors, generators, and appliances in Class III locations shall be provided with dusttight enclosures ______.
a. complying with the temperature limitations in Section 503.5
b. listed for the location
c. suitable for the location
d. none of the above
NEC REF:
a. complying with the temperature limitations in Section 503.5
503.120
Ventilating pipes for motors, generators, or other rotating electrical machinery, or for enclosures for electric equipment, installed in Class III locations, shall be of metal not less than 0.53 millimeters (0.021 inches) in thickness, or ______.
a. an assembly listed for the location
b. enclosed in a one hour fire-rated assembly
c. of equally substantial noncombustible material
d. a. or b.
NEC REF:
c. of equally substantial noncombustible material
503.128
Each luminaire used in Class III locations shall be clearly marked to show the maximum wattage of the lamps that is permitted without exceeding an exposed surface temperature of ______, under normal conditions of use.
a. 165°F
b. 185°C
c. 329°C
d. 329°F
NEC REF:
d. 329°F
503.130(A)
Flexible cords permitted for use in Class III locations must ______.
I. be of a type listed for hard usage
II. be supported in such a manner that there will be no tension on the cord
III. be terminated with a dusttight cord connector
IV. contain an equipment grounding conductor complying with 400.23
a. I.
b. I., II., and III.
c. I., II., III., and IV.
d. I., III., and IV.
e. IV.
NEC REF:
e. IV.
503.140
Note: Section 503.140 requires the cord to be of the extra-hard usage type; choice I. indicates hard usage. The cord must be supported in a manner to eliminate tension on the terminal connections and not the cord, which is listed in choice II. The cord connector must be listed as dusttight and not just dusttight, which is what is stated in choice III. The only correct answer is IV.
In Class III locations, where _______ only moderate accumulations of lint or flyings are likely to collect in the vicinity of a receptacle, and where such receptacle is readily accessible for routine cleaning, general purpose grounding-type receptacles mounted so as to minimize the entry of fibers/flyings shall be permitted.
a. in the judgment of the authority having jurisdiction
b. it is likely that
c. special permission is granted and
d. none of the above
NEC REF:
a. in the judgment of the authority having jurisdiction
503.145 Exception
The power supply to contact conductors of electric cranes, hoists, and similar equipment, installed in Class III locations, shall be electrically isolated from all other systems, ______, and shall be equipped with an acceptable ground detector.
a. grounded
b. listed for the locations
c. suitable for the location
d. ungrounded
NEC REF:
d. ungrounded
503.155(A)
Rooms for storage battery charging equipment located in Class III locations shall be constructed to prevent the entrance of ignitible amounts of flyings or lint and shall ______.
a. be equipped with fire sprinklers
b. be of 1-hour fire-rated construction
c. be well ventilated
d. have fire-rated doors
e. b. and d.
NEC REF:
c. be well ventilated
503.160
Associated apparatus is apparatus in which the circuits are not necessarily intrinsically safe themselves but that affects the characteristics of the intrinsically safe circuits and is relied on to maintain intrinsic safety.
a. True
b. False
NEC REF:
False
100
Simple apparatus is an electrical component or combination of components of simple construction with well-defined electrical parameters that does not generate more than 1.5 volts, 100 milliamperes, and 25 milliwatts, or a passive component that does not dissipate more than 1.5 watts and is compatible with the intrinsic safety of the circuit in which it is used.
a. True
b. False
NEC REF:
False
100
A control drawing is a drawing or other document provided by the manufacturer of the intrinsically safe or associated apparatus, or of the nonincendive field wiring apparatus or associated nonincendive field wiring apparatus, that details the ______ interconnections between the intrinsically safe and associated apparatus or between the nonincendive field wiring apparatus or associated nonincendive field wiring apparatus.
a. allowed
b. circuit
c. equipment
d. required
NEC REF:
a. allowed
100
A simple apparatus, whether shown on the control drawing(s) or not, is permitted to be installed, provided the simple apparatus ______ intrinsically safe circuits.
a. does not interconnect
b. interconnects
c. is connected to
d. is part of the
NEC REF:
a. does not interconnect
504.10(A)
Simple apparatus components with a surface area smaller than 10 square centimeters (cm2) (excluding lead wires) may be classified as ______ if their surface temperature does not exceed 150°C.
a. T3
b. T4
c. T5
d. none of the above
NEC REF:
c. T5
504.10(D)
One of the methods permitted to provide the required separation between the conductors of intrinsically safe circuits and conductors of nonintrinsically safe circuits in enclosures is to separate them by at least ______ and secure them.
a. 2”
b. 3”
c. 4”
d. 6”
NEC REF:
a. 2”
504.30(A)(2)
Associated apparatus and cable shields shall be grounded in accordance with ______.
a. Article 250
b. the listing and labeling
c. the required control drawing
d. none of the above
NEC REF:
c. the required control drawing
504.50(B)
Raceways, cable trays, and other wiring methods for intrinsically safe system wiring shall be identified with permanently affixed labels with the wording “Intrinsic Safety Wiring” or equivalent with a spacing between labels not more than ______.
a. 10’
b. 15’
c. 25’
d. 30’
NEC REF:
c. 25’
504.80(B)
In Class III locations, ______ shall be of the grounding type, shall be designed so as to minimize the accumulation or the entry of fibers/flyings, and shall prevent the escape of sparks or molten particles.
a. attachment plugs
b. receptacles
c. switches
d. a. and b.
e. a., b., and c.
NEC REF:
d. a. and b.
503.145
