Lesson 3: The Requirements For Electrical Installations In Class I Hazardous (Classified) Locations Flashcards
Threaded rigid metal conduit, threaded steel intermediate conduit, and electrical metallic conduit are permitted to be used in Class I, Division 1 locations.
a. True
b. False
NEC REF:
B. False
501.10(A)(1)(1)
Type PVC conduit, Type RTRC conduit, and Type HDPE conduit shall be permitted where encased in a concrete envelope a minimum of two inches thick and provided with not less than ______ of cover measured from the top of the conduit to grade.
a. 2”
b. 24”
c. 50”
d. 50 mm
NEC REF:
b. 24”
501.10(A)(1)(2)
Note: The permission to use PVC, RTC, and HDPE was located in an exception to 501.10(A)(1)(2) in the 2020 NEC. CMP-14 determined the exception should be turned into positive code language. The 2023 NEC Style Manual: “2.1.9.1 Usage. Exceptions shall convey alternatives or differences to a basic requirement. Exceptions to requirements shall be used sparingly. The technical committee shall determine when a code requirement is most effective as positive code language or as an exception.”
Where Type MI cable is used in Class I, Division 1 locations, it shall be installed and supported in a manner to avoid ______ at the termination fittings.
a. being subject to physical damage
b. loose connections
c. tensile stress
d. none of the above
NEC REF:
c. tensile stress
501.10(A)(1)(3)
All boxes and fittings installed in a Class I, Division 1 location must be listed for Class I, Division 1 locations.
a. True
b. False
NEC REF:
b. False
501.10(A)(3)
Type PLTC cable or Type PLTC-ER cable used for ______ circuits, including installation in cable tray systems are permitted in Class I, Division 2 locations.
a. Class 1
b. Class 2
c. Class 3
d. b. and c.
e. a., b., and c.
NEC REF:
d. b. and c.
501.10(B)(1)(3)
Note: The 2020 NEC includes Class 1, which has been there since the addition of PLTC as an approved wiring method. The inclusion of Class 1 was an error that was addressed in a PI from the IBEW members of CMP-14. The substantiation cited UL 13: Power Limited Circuit Conductors, which shows PLTC to be listed for 300 volts maximum and is only permitted to be used for Class 2 and Class 3 circuits.
Listed Type P cable with or without metal braid armor, with an overall jacket, and terminated with fittings listed for the location when entering explosionproof, flameproof, or pressurized equipment and that is installed in accordance with Part II of Article 337 is permitted in all Class I, Division 2 locations.
a. True
b. False
NEC REF:
b. False
501.10(B)(1)(9)
Note: The answer to the question is false because Type P cable can only be used in restricted industrial establishments, which is stated in 501.10(B)(1)(9). It is not permitted for all Class I, Division 2 locations.
Flexible cord listed for hard usage and terminated with listed fittings, with a conductor for use as an equipment grounding conductor is permitted for flexible connections in Class I, Division 2 locations.
a. True
b. False
NEC REF:
b. False
501.10(B)(2)(6)
Note: The answer is false because the requirement in 501.10(B)(2)(6) requires the cord to be listed for extra-hard usage.
Nonincendive field wiring systems shall be installed in accordance with the ______.
a. control drawings
b. electrical control schematics
c. project blueprints
d. project specifications
NEC REF:
a. control drawings
501.10(B)(3)
Sealing compound must be used in Type ______ cable termination fittings to exclude moisture and other fluids from the cable insulation.
a. MC
b. MI
c. TC
d. None of the above
NEC REF:
b. MI
501.15
Seals are required in each conduit entry into an enclosure containing apparatus, such as switches, circuit breakers, fuses, relays, or resistors that may produce arcs, sparks, or temperatures that exceed 80% of the ______, in degrees Celsius, of the gas or vapor involved in normal operation.
a. autoignition temperature
b. flashpoint
c. upper flammable limit
d. none of the above
NEC REF:
a. autoignition temperature
501.15(A)(1)(1)
Enclosures installed in Class I locations, identified for the location, and marked “Leads Factory Sealed,” “Factory Sealed,” “Seal not Required,” or the equivalent, shall not be considered to serve as a seal for another ______ enclosure that is required to have a conduit seal.
a. adjacent
b. approved
c. explosionproof
d. listed
NEC REF:
a. adjacent
501.15(A)(1)(2)
Where two or more explosionproof enclosures that require conduit seals are connected by nipples or runs of conduit not more than ______ long, a single conduit seal in each such nipple connection or run of conduit shall be considered sufficient.
a. 24”
b. 30”
c. 36”
d. none of the above
NEC REF:
c. 36”
501.15(A)(3)
The sealing fitting required to be installed in conduit runs leaving a Class I, Division 2 location shall be permitted to be installed on either side of the boundary within ______ of the boundary.
a. 6’
b. 10’
c. 18’
d. 36’
NEC REF:
b. 10’
501.15(B)(2)
The melting point of the sealing compound used for sealing fittings in Class I, Division 1 and Class I, Division 2 locations shall not be less than ______.
a. 150°C
b. 150°F
c. 200°C
d. 200°F
NEC REF:
d. 200°F
501.15(C)(2)
Multiconductor or optical multifiber cables with a gas/vaportight continuous sheath capable of transmitting gases or vapors through the cable core that enter enclosures in a Division 2 location shall be sealed with a listed fitting after the jacket and any other coverings have been removed. Removal of shielding material from shielded cables and separation of twisted pair cables shall not be required if the conductors are sealed in accordance with instructions provided with the ______ fitting.
a. approved
b. identified
c. listed
d. suitable
NEC REF:
c. listed
501.15(E)(1) Exception No. 2
A process seal shall be a device that prevents the ______ of process fluids from the designed containment into the external electrical system.
a. migration
b. mitigation
c. passage
d. transfer
NEC REF:
a. migration
501.17
There shall be no uninsulated exposed parts, such as electrical conductors, buses, terminals, or components, that operate at more than ______ ( ______ in wet locations) installed in Class I, Division 1 or Class I, Division 2 locations.
a. 24 V / 12 V
b. 24 V / 15 V
c. 30 V / 15 V
d. 30 V / 24 V
e. none of the above
NEC REF:
c. 30 V / 15 V
501.25
The locknut-bushing and double-locknut types of contacts are not permitted to be used for bonding purposes in Class I, Division 1 or Class I, Division 2 locations.
a. True
b. False
NEC REF:
a. True
501.30(B)(1)(a)
Transformers and capacitors that do not contain a liquid that will burn may be installed in Class I, Division 1 locations where they are installed in vaults complying with 501.100(A)(1) or ______ for Class I locations.
a. approved
b. identified
c. labeled
d. listed
NEC REF:
b. identified
501.100(A)(2)
General-purpose assemblies approved for use in Class I, Division 2 locations must be clearly and permanently marked with the maximum obtainable surface temperature if it exceeds 100°C unless it is alternatively marked to indicate the temperature class for which it is ______, using the temperature class (T Code) of Table 500.8(C)(4).
a. identified
b. labeled
c. listed
d. suitable
NEC REF:
d. suitable
501.105(B)(1)
Fused or unfused disconnect and isolating switches for transformers or capacitor banks that are not intended to interrupt current in the normal performance of the function for which they are installed shall be permitted to be installed in ______ enclosures.
a. approved
b. general-purpose
c. identified
d. suitable
NEC REF:
b. general-purpose
501.115(B)(2)
Totally enclosed motors of the types specified in 501.125(A)(2) or (A)(3) installed in Class I, Division 1 locations shall have no external surface with an operating temperature in degrees Celsius in excess of ______ the autoignition temperature of the gas or vapor involved.
a. 75%
b. 80%
c. 85%
d. 90%
NEC REF:
b. 80%
501.125(A)
Pendant luminaire support stems longer than 12 in. must have permanent and effective bracing against lateral displacement, which shall be provided at a level not more than 12 in. above the lower end of the stem, or flexibility in the form of a fitting or flexible connector ______ for the Class I, Division 1 location, must be provided not more than 12 in. from the point of attachment to the supporting box or fitting.
a. approved
b. identified
c. listed
d. suitable
NEC REF:
b. identified
501.130(A)(3)
In Class I, Division 1 locations or in Class I, Division 2 locations where boxes, fittings, or enclosures are required to be explosionproof, flexible cords shall be terminated with cord connectors or attachment plugs listed for the location or listed cord connectors installed with seals listed for the location.
a. True
b. False
NEC REF:
a. True
501.140(B)(4)
