153 Questions
Which one of the following is NOT considered an effective ground-fault current path according to the information provided?
Flexible metallic tubing terminated in listed fittings
According to the information provided, what is the maximum combined length of flexible metal conduit, flexible metallic tubing, and liquidtight flexible metal conduit allowed in the same effective ground-fault current path?
1.8 m (6 ft)
According to the information provided, which one of the following is NOT listed as an effective ground-fault current path?
Liquidtight flexible metal conduit
According to the text, which of the following conductors is NOT permitted to be used as equipment grounding conductors?
Structural metal frame of a building or structure
According to the text, which of the following is a requirement for equipment grounding conductors (EGCs)?
EGCs must be a wire-type conductor
According to the text, which of the following is NOT a permitted identification for equipment grounding conductors?
Red
According to the text, which of the following is NOT a requirement for equipment grounding conductors 4 AWG and larger?
Stripping the insulation from the entire exposed length
According to the text, what color should the outer finish of equipment grounding conductors in flexible cords be?
Green with yellow stripes
According to the text, where should equipment grounding conductors of bare or covered aluminum or copper-clad aluminum not be installed?
All of the above
According to the text, where should aluminum or copper-clad aluminum conductors external to buildings or enclosures not be terminated?
Within 450 mm (18 in.) of the earth
According to the text, what is the minimum size of equipment grounding conductors of the wire type?
As specified in Table 250.122
Which one of the following is NOT true about the equipment grounding conductor (EGC) in a parallel arrangement with two nonmetallic conduits installed underground?
The EGC in each cable is required to be sized in accordance with 250.122 based on the rating or setting of the OCPD that is protecting the conductors connected in parallel
Which one of the following is NOT a requirement for the equipment grounding conductor (EGC) in a parallel arrangement with nonmetallic conduits installed underground?
The EGC in each raceway must be connected together at each end of the circuit
What is the minimum size of the equipment grounding conductor (EGC) required for grounding raceway and equipment with a rating or setting of 2000 amperes?
350
Which one of the following is NOT a requirement for the identification of wiring device terminals for the equipment grounding conductor (EGC)?
A green, readily removable terminal screw with a hexagonal head
According to Table 250.122, what is the required size for the equipment grounding conductor for three 3-phase circuits with overcurrent devices rated 30, 60, and 100 amperes?
8 AWG copper or 6 AWG aluminum conductor or copper-clad aluminum conductor
According to 250.122(D)(1) or (D)(2), how should the equipment grounding conductors for motor circuits be sized?
In accordance with 250.122(D)(1) or (D)(2)
What is the minimum size for the equipment grounding conductor in a flexible cord with the largest circuit conductor 10 AWG or smaller?
18 AWG copper
If conductors are installed in multiple raceways and connected in parallel, how should the wire-type equipment grounding conductor be installed?
In each raceway and connected in parallel
Which one of the following is true about equipment grounding conductor connections at the source of separately derived systems?
They should be made in accordance with 250.30(A)(1)
When replacing non-grounding-type receptacles with grounding-type receptacles, the equipment grounding conductor can be connected to which of the following?
The equipment grounding terminal bar within the enclosure where the branch circuit originates
Which section of the code applies to both ungrounded and grounded systems, but is most commonly used for receptacle replacement or branch-circuit extensions in single-phase, 120-volt, 15- and 20-ampere branch circuits?
250.130(C)
What is the requirement for isolated sections of metal raceway or cable armor if they need to be connected to an equipment grounding conductor?
They should be connected in accordance with 250.134
Which one of the following is NOT a method for connecting grounded enclosures to an equipment grounding conductor?
Running the equipment grounding conductor separately from the circuit conductors
According to the text, why is it beneficial to run the equipment grounding conductor in the same raceway or cable as the circuit conductors?
To increase the magnetic flux cancellation between the circuit conductor and the equipment grounding conductor
According to the text, what is the relationship between the strength of the magnetic flux and the distance between the circuit conductor and the equipment grounding conductor?
The strength of the magnetic flux is inversely proportional to the square of the distance
Which of the following is a correct statement about the grounding electrode conductor connection for a separately derived system?
The grounding electrode conductor connection can be made at any point on the separately derived system from the source to the first system disconnecting means or overcurrent device.
What determines the size of the grounding electrode conductor?
The size of the grounding electrode
Where can the grounding electrode conductor connection be made for a separately derived system that has no disconnecting means or overcurrent devices?
The grounding electrode conductor connection must be made at the source of the separately derived system.
According to the information provided, what is the maximum number of insulating washers that can be removed from a receptacle without a contact yoke or device to ensure direct metal-to-metal contact?
Two
According to the text, when can a listed exposed work cover be used as the grounding and bonding means?
Both of the above
According to the text, when can an equipment bonding jumper be omitted?
Both of the above
According to the text, what is the purpose of an isolated-ground-type receptacle?
To reduce electromagnetic interference on the equipment grounding conductor
According to the information provided, what is the maximum size for the grounding electrode conductor for a direct-current (dc) system?
3/0 copper or 250 kcmil aluminum or copper-clad aluminum
According to the text, where should the grounding connection for direct-current (dc) systems supplied from an off-premises source be made?
At one or more supply stations
According to the text, what is the minimum size for the grounding electrode conductor for a direct-current (dc) system if the system consists of a 3-wire balancer set or a balancer winding with overcurrent protection?
8 AWG copper or 6 AWG aluminum or copper-clad aluminum
According to the text, what is the minimum size for the grounding electrode conductor for a direct-current (dc) system if the system is other than a 3-wire balancer set or a balancer winding with overcurrent protection?
8 AWG copper or 6 AWG aluminum or copper-clad aluminum
According to the text, when terminating an isolated EGC at a separate building, what potential hazard could exist during lightning transients?
Large voltage difference between buildings
According to 250.148, if multiple circuits are spliced within a box or terminated to equipment within the box, what must be done with the equipment grounding conductors (EGCs)?
They must be connected together and to the box
According to 250.162(A), when should a 2-wire, direct-current system supplying premises wiring be grounded?
When operating at greater than 60 volts but not greater than 300 volts
According to the text, what is the required size for the equipment grounding conductor (EGC) for grounding raceway and equipment with a rating or setting of 2000 amperes?
250 kcmil copper or 3/0 AWG aluminum
Which one of the following is NOT a requirement for grounding non-current-carrying metal parts of new appliance installations?
A new range or clothes dryer connected to an existing branch circuit without an EGC must have an appliance bonding jumper connected between the neutral terminal and the frame of the appliance
According to 250.142(A), where is a grounded circuit conductor permitted to be connected to non-current-carrying metal parts of equipment, raceways, and other enclosures?
On the supply side or within the enclosure of the ac service disconnecting means
According to 250.144, if equipment is required to be grounded and is supplied by more than one circuit containing an equipment grounding conductor, what must be provided?
A means to terminate each equipment grounding conductor
What is the effect of re-grounding the grounded circuit conductor on the load side of the service and disconnecting the grounded conductor at any point on the line side of the service?
The EGC and all conductive parts connected to it would become energized
Which of the following is a requirement for equipment grounding conductor connections for non-current-carrying metal parts of cord-and-plug-connected equipment?
The equipment grounding conductor must be run with the power supply conductors in a cable assembly or flexible cord properly terminated in a grounding-type attachment plug with one fixed grounding contact.
According to the information provided, what is the minimum size of the equipment grounding conductor required for frames of ranges, wall-mounted ovens, counter-mounted cooking units, clothes dryers, and outlet or junction boxes that are part of the circuit?
10 AWG copper or 8 AWG aluminum or copper-clad aluminum
Which of the following is NOT a condition that must be met for the grounded conductor to be permitted to be connected to the frame of an appliance in existing branch-circuit installations?
The grounded conductor is part of a Type SE service-entrance cable that originates in equipment other than a service.
According to the text, what is the maximum voltage between any two conductors or between any conductor and ground on which the grounding contacting pole of grounding-type plug-in ground-fault circuit interrupters can be of the movable, self-restoring type?
150 volts
According to the text, what is the purpose of an isolated-ground-type receptacle?
To provide a separate grounding path for sensitive electronic equipment
According to the text, what determines the size of the grounding electrode conductor?
The size of the electrical service
According to the information provided, what is the maximum combined length of flexible metal conduit, flexible metallic tubing, and liquidtight flexible metal conduit allowed in the same effective ground-fault current path?
10 feet
According to the text, what is the minimum size of the equipment grounding conductor for secondary circuits of instrument transformers and for instrument cases?
12 AWG copper or 10 AWG aluminum or copper-clad aluminum
According to the text, what is the minimum insulation level for neutral conductors of solidly grounded systems?
600 volts
According to the text, what is the ampacity requirement for the neutral conductor in a solidly grounded system?
Not less than the load imposed
According to the text, what is the maximum number of insulating washers that can be removed from a receptacle without a contact yoke or device to ensure direct metal-to-metal contact?
3
Which one of the following is NOT an exception to the requirement of grounding secondary circuits of current and potential instrument transformers?
Circuits where the primary windings are connected to circuits of 300 volts or more to ground
According to the text, when should the cases or frames of instrument transformers be connected to the equipment grounding conductor?
If accessible to other than qualified persons
According to the text, which of the following is a requirement for instruments, meters, and relays operating at 1000 volts or less?
Cases and other exposed metal parts connected to the equipment grounding conductor
According to the text, what is the maximum distance between any two adjacent grounding electrodes in a multigrounded neutral system?
400 m (1300 ft)
According to the text, when should a grounding electrode conductor be connected to the multigrounded neutral conductor in a multigrounded neutral system?
At each transformer and at other additional locations
According to the text, what is the purpose of connecting the shielding in a multigrounded shielded cable system to a grounding electrode?
To protect against electromagnetic interference (EMI)
According to 250.186(A), what is the requirement for the size of the solidly grounded circuit conductor(s) in a service-supplied alternating-current system?
The larger of that determined by 250.184 or 250.186(A)(1) or (A)(2)
According to the text, what is the maximum voltage developed between the frame of portable or mobile equipment and ground by the flow of maximum ground-fault current?
100 volts
According to the text, what is the minimum size for the grounding electrode conductor if it connects non-current-carrying metal parts to ground?
6 AWG copper
According to the text, what is the maximum number of insulating washers that can be removed from a receptacle without a contact yoke or device to ensure direct metal-to-metal contact?
1 washer
According to the text, what is the maximum combined length of flexible metal conduit, flexible metallic tubing, and liquidtight flexible metal conduit allowed in the same effective ground-fault current path?
20 feet
According to the text, which type of cable shield can be used as an EGC in a solidly grounded system if the metallic shield will not be damaged during the time it takes to open the circuit OCPD?
Concentric neutral cable
According to the information provided, where should a separate EGC be installed if the cable shield cannot carry ground-fault current without damage?
Outside the cable assembly
According to 250.191, what is the grounding system requirement for AC substations?
Grounding system shall be in accordance with Part III of the article and IEEE 80
According to 250.194, what is the requirement for grounding and bonding of metal fences and other metal structures in or surrounding a substation with exposed electrical conductors and equipment?
Metal fences and other metal structures shall be bonded to the grounding electrode system with wire-type bonding jumpers and gates shall be bonded to the gate support post, and any gate or other opening in the fence shall be bonded across the opening by a buried bonding jumper
According to the text, what is the minimum size of the grounded conductor for a single raceway or overhead conductor?
Not smaller than the largest ungrounded service-entrance conductor(s)
According to the text, what is the minimum size of the grounded conductor for parallel conductors in two or more raceways or overhead conductors?
1/0 AWG
According to the text, what is the relationship between the ampacity of the grounded conductor and the ungrounded conductors in a 3-phase, 3-wire delta service?
The ampacity of the grounded conductor shall not be less than that of the ungrounded conductors
According to the text, what are the conditions that must be met for impedance grounded systems to be permitted?
Conditions of maintenance and supervision ensure that only qualified persons service the installation, ground detectors are installed on the system, and line-to-neutral loads are not served
According to Article 300, which of the following is NOT an integral part of equipment and therefore subject to the requirements of this article?
Conductors forming part of listed utilization equipment
According to Article 300, where can the wiring requirements within boxes, conduit bodies, and fittings be found?
Chapter 3 article governing that particular wiring method
According to Table 300.1(C), what should be in accordance with metric designators and trade sizes?
Conduit, tubing, and fittings
According to the information provided, what is the maximum depth required for direct burial of underground installations with no vehicular traffic and a concrete slab extending not less than 152 mm (6 in.) beyond the installation?
150 mm (6 in.)
According to the text, what is the maximum depth allowed for pool, spa, and fountain lighting installed in a nonmetallic raceway, limited to not more than 30 volts, and part of a listed low-voltage lighting system?
100 mm (4 in.)
According to the text, what is the maximum depth required for underground installations under streets, highways, roads, alleys, driveways, and parking lots?
600 mm (24 in.)
According to the text, what is the minimum thickness of a steel plate that can be used to provide protection against nail or screw penetration for cables and raceways installed in shallow grooves?
1/16 in.
According to the text, what is the minimum distance required between the lowest surface of metal-corrugated sheet roof decking and the top of a cable, raceway, or box installed in exposed or concealed locations?
1/16 in.
According to the text, what is the maximum thickness of a listed and marked steel plate that can be used to provide protection against nail or screw penetration for cables and raceways installed in shallow grooves?
1.6 mm
According to the text, what is the minimum distance required between the lowest surface of metal-corrugated sheet roof decking and the top of a cable, raceway, or box installed in exposed or concealed locations?
1/16 in.
According to the text, what is the minimum distance that bored holes for cable- or raceway-type wiring methods must be from the edges of wood members?
32 mm (11/4 in.)
According to the text, what is the maximum voltage rating required for the insulation of conductors in a raceway for systems of 1000 volts or less?
The maximum insulation voltage rating of the conductors in the raceway
According to the text, what is the maximum voltage rating for conductors of circuits rated over 1000 volts ac, 1500 volts dc, nominal?
1500 volts ac
According to the text, where should aluminum or copper-clad aluminum conductors external to buildings or enclosures not be terminated?
Grounding electrode conductor
According to the text, what is the minimum thickness of a steel plate required to protect cables or raceways from nail or screw penetration?
1.6 mm (1/16 in.)
According to the text, which of the following types of conduit does NOT require a steel plate to protect against nail or screw penetration?
Rigid metal conduit
According to the text, in both exposed and concealed locations, what is the minimum distance that a cable or raceway should be installed from the nearest edge of a framing member or furring strip where nails or screws are likely to penetrate?
32 mm (1 1/4 in.)
According to the text, what is the minimum thickness of a steel plate, sleeve, or equivalent required to protect a cable or raceway from nail or screw penetration if the minimum distance from the framing member or furring strip cannot be maintained?
1.6 mm (1/16 in.)
According to the text, what is the purpose of metric designators in identifying the size of a circular raceway?
To provide a modular or relative measure of the conduit
According to the text, what is the requirement for threaded joints on circular raceways?
Threaded joints must be threaded to the traditional dimension of ¾-inch taper per foot
According to the text, what wiring methods can be used for voltage levels of 1000 volts ac, 1500 volts dc, nominal, or less?
Wiring methods specified in Chapter 3
According to the text, where should all conductors of the same circuit and the grounded conductor be contained?
In the same raceway or conduit body
Which one of the following is a requirement for protecting heavy conductors and cables at raceway terminating points?
Using insulating bushings or fittings with rounded edges
What is the purpose of using insulating bushings or fittings with rounded edges at raceway and cable terminations?
To reduce the risk of insulation failure at conductor insulation stress points
What is the temperature rating requirement for insulating bushings or fittings used to protect heavy conductors and cables?
Not less than the insulation temperature rating of the installed conductors
What should be used to secure a fitting or raceway when protecting heavy conductors and cables?
Separation from the fitting or raceway using an identified insulating material
According to Table 300.5(A), what is the minimum depth required for conductors under residential driveways?
18 inches
According to the text, what is the maximum voltage rating for conductors of circuits rated over 1000 volts ac, 1500 volts dc, nominal?
2000 volts
According to the text, what is the maximum depth allowed for pool, spa, and fountain lighting installed in a nonmetallic raceway, limited to not more than 30 volts, and part of a listed low-voltage lighting system?
12 inches
According to the text, which section of the code provides requirements for cable and raceway supporting?
Article 300
According to the text, what is the maximum voltage rating required for the insulation of conductors in a raceway for systems of 1000 volts or less?
1000 volts
According to the text, what is the requirement for protecting heavy conductors and cables at raceway terminating points?
Use insulating bushings or fittings with rounded edges
According to the text, what materials should not be placed in an excavation to prevent damage to raceways, cables, conductors, or other substructures?
Backfill containing large rocks
According to the text, what should be used to protect raceways, cables, or conductors from physical damage?
Granular or selected material
According to the text, what should be used to seal or plug conduits or raceways through which moisture might contact live parts?
Sealants
According to the text, what is the purpose of an isolated phase installation in AC circuits?
To limit available fault current at downstream equipment
According to the information provided, what is the formula for determining the change in length of a conduit due to temperature change?
Change in length = coefficient of expansion x change in temperature x initial length
According to the text, what is the key factor in determining any temperature-related change in conduit length?
Coefficient of expansion of the conduit material
According to the text, what is the purpose of the coefficient of expansion in the formula for determining the change in length of a conduit?
To account for the material's expansion or contraction with temperature change
According to the information provided, what is the relationship between the change in length of a conduit and the initial length of the conduit?
Directly proportional
According to the text, what is the minimum airspace required between the wiring system and the wall or supporting surface in wet locations?
4 mm
According to the text, what type of raceways, boxes, and fittings are permitted to be installed without airspace in wet locations on a concrete, masonry, tile, or similar surface?
Nonmetallic raceways, boxes, and fittings
According to the text, what is the purpose of sealing a raceway or sleeve in areas with temperature differences and condensation problems?
To prevent the circulation of warm air to a colder section of the raceway or sleeve
According to the text, what type of fittings should be provided in raceways to compensate for thermal expansion, deflection, and contraction?
All of the above
Which one of the following is NOT required to be protected against corrosion and deterioration according to the text?
Support hardware
Which one of the following materials is NOT required to be suitably protected against corrosion inside and outside, except threads at joints, for ferrous metal equipment according to the text?
Nipples
Which one of the following materials does NOT require protective coatings for corrosion according to the text?
Stainless steel
Which one of the following materials is required to have supplementary corrosion protection according to the text?
Aluminum raceways
Which one of the following is NOT true about the requirements for conductors installed in underground locations?
Conductors must comply with 310.10(C).
According to the information provided, where should Type MI cable be permitted to be installed under a building without installation in a raceway?
Embedded in concrete, fill, or other masonry.
According to the text, what is the purpose of a warning ribbon placed in the trench above underground service conductors that are not encased in concrete?
To identify the location of the conductors.
According to the text, what is the requirement for protecting conductors emerging from grade in underground installations?
The protection must extend from the minimum cover distance below grade to a point at least 2.5 m (8 ft) above finished grade.
According to the text, which of the following is NOT a requirement for grounding non-current-carrying metal parts of new appliance installations?
The grounding conductor shall be insulated
According to the text, what is the maximum depth allowed for pool, spa, and fountain lighting installed in a nonmetallic raceway, limited to not more than 30 volts, and part of a listed low-voltage lighting system?
200 mm (8 in.)
According to the text, what is the purpose of metric designators in identifying the size of a circular raceway?
To indicate the cross-sectional area of the raceway
According to the text, what is the maximum number of insulating washers that can be removed from a receptacle without a contact yoke or device to ensure direct metal-to-metal contact?
4
According to the text, what is the maximum thickness of a listed and marked steel plate that can be used to provide protection against nail or screw penetration for cables and raceways installed in shallow grooves?
3/8 inch
According to the text, what is the minimum size for the grounding electrode conductor if it connects non-current-carrying metal parts to ground?
1/0 AWG
According to the text, what is the maximum voltage rating for conductors of circuits rated over 1000 volts ac, 1500 volts dc, nominal?
3000 volts
Which one of the following is NOT a requirement for marking products as 'suitable for use in other spaces for environmental air' according to the NEC?
The marking must comply with requirements in Section 300.22(C)
According to the text, which one of the following is NOT a type of duct where no wiring systems of any type shall be installed?
Ducts used for ventilation of commercial-type cooking equipment
According to the text, where can equipment, devices, and wiring methods specified in this section be permitted within?
Ducts specifically fabricated for environmental air
According to the text, what is the purpose of raceways in electrical installations?
To provide physical protection for conductors
According to the text, what is the requirement for installing raceways prior to the installation of conductors or cables?
Raceways other than busways, listed manufactured assemblies, or exposed raceways with hinged or removable covers must be installed complete
According to the text, what is the maximum vertical rise allowed for unsupported conductors in vertical raceways?
Refer to Table 300.19(A) for specific values
According to the text, when can metal raceways be supported, terminated, or connected by welding?
Only when specifically designed or permitted in the Code
According to the text, what is the maximum distance for supporting conductors in vertical raceways for 6 AWG through 1/0 AWG copper conductors?
60 m
According to the text, what is the maximum distance for supporting conductors in vertical raceways for 2/0 AWG through 4/0 AWG aluminum conductors?
55 m
According to the text, what is the maximum distance for supporting conductors in vertical raceways for over 500 kcmil through 750 kcmil copper conductors?
120 m
According to the text, what is the maximum distance for supporting conductors in vertical raceways for over 750 kcmil aluminum conductors?
26 m
According to the text, what is the purpose of firestopping openings around electrical penetrations into or through fire-resistant-rated walls, partitions, floors, or ceilings?
To prevent the spread of fire and products of combustion
According to the information provided, where can valuable information concerning application, installation, and use of firestop systems and firestop devices be found?
In the UL Guide Information for Electrical Equipment
According to the text, what must be evaluated when providing openings for penetrating items in fire-rated construction?
The structural integrity of the floor or wall assembly
According to Article 300.22, which spaces are subject to the requirements for the installation and use of electrical wiring and equipment?
Ducts used for dust, loose stock, or vapor removal; ducts specifically fabricated for environmental air; and other spaces used for environmental air (plenums)
According to the text, when is a box or conduit body not required for splices, junctions, switches, terminations, or outlet points in wiring methods with removable covers?
When using wireways with removable covers
According to the text, when can a box or conduit body be omitted for cables entering or exiting from conduit or tubing used for cable support or protection against physical damage?
When a fitting is provided on the end(s) of the conduit or tubing to protect the cable from abrasion
According to the text, when can a box or conduit body be omitted for straight-through splices in mineral-insulated metal-sheathed cable?
When accessible fittings are used
According to the text, when can a box or conduit body be omitted for wiring devices with integral enclosures?
When the wiring device has integral enclosure identified for the use and securely fastened to walls or ceilings
Test your knowledge on sizing electrical ground conductors (EGCs) for multiple circuits in this quiz. Learn when and how to size an EGC based on the largest circuit OCPD supplied.
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