128 Questions
According to the text, what is the minimum size for the common grounding electrode conductor for a separately derived system?
3/0 AWG copper or 250 kcmil aluminum
According to the text, how should tap connections to the common grounding electrode conductor be made?
Using a busbar
According to the text, when is a common grounding electrode conductor permitted to be used for a separately derived system?
When the source of the system is located within equipment suitable for use as service equipment
According to the text, how should metal enclosures of a separately derived system be connected to the grounding electrode?
Using a grounding electrode conductor of sufficient size
According to the text, what is the minimum ampacity requirement for the impedance grounding conductor?
8 AWG copper or 6 AWG aluminum or copper-clad aluminum
What is the purpose of fully insulating the impedance grounding conductor?
To prevent electrical shocks
What is the impedance grounding conductor connected to?
Grounding impedance
Which of the following is required for grounding of ungrounded separately derived systems?
Grounding electrode conductor
What is the purpose of a grounding electrode connection for an outdoor source of a separately derived system?
To provide a first line of defense against overvoltages
When is a grounding electrode system and grounding electrode conductor not required for a building or structure supplied by a feeder or branch circuit?
When there is only a single branch circuit supplying the building or structure
What is the purpose of an equipment grounding conductor in a grounded system supplied by a feeder or branch circuit?
To ground or bond equipment, structures, or frames
Which one of the following is a requirement for using the grounded conductor as the ground-fault return path in compliance with previous editions of the Code?
Ground-fault protection of equipment has been installed on the supply side of the feeder(s)
What is the purpose of installing an equipment grounding conductor (EGC) with the supply circuit conductors?
To ensure that normal circuit current is not imposed on continuous metal paths
In what situation is an equipment grounding conductor (EGC) required to be installed with feeder conductors in a separately derived system?
When overcurrent protection is provided where the conductors originate
What is used to complete the ground-fault current path between the source and the building or structure supplied in a separately derived system where an overcurrent protection device (OCPD) is not located at the source?
A supply-side bonding jumper
According to the text, what is the purpose of connecting the grounding electrode(s) to the building or structure disconnecting means?
To comply with 250.32(C)(1)
In which situation should overcurrent protection be provided where the conductors originate?
When the conductors are supplied by a separately derived system
What should be done if one or more disconnecting means supply one or more additional buildings or structures under single management and are located remote from those buildings or structures?
An equipment grounding conductor should be run with the circuit conductors
What is the purpose of the equipment grounding conductor in a separate building or structure?
To bond normally non-current-carrying metal parts of equipment
According to the text, under what conditions is the frame of a vehicle or trailer not required to be connected to a grounding electrode?
The generator supplies both equipment located on the vehicle or trailer and cord-and-plug-connected equipment through receptacles mounted on the vehicle, trailer, or on the generator
What type of conductor should be installed with the supply conductors from a permanently installed generator(s) to the first disconnecting mean(s)?
Equipment grounding conductor
What is the purpose of a ground detector in an impedance grounded system?
To detect ground faults
Where should the grounding impedance device be installed in an impedance grounded system?
Between the grounding electrode conductor and the impedance grounding conductor
Which one of the following is a requirement for using the grounded conductor as the ground-fault return path in compliance with previous editions of the Code?
The grounded conductor must be connected to the equipment grounding terminal.
According to the text, under what conditions is the frame of a vehicle or trailer not required to be connected to a grounding electrode?
When the vehicle or trailer is not supplied by a feeder or branch circuit.
According to the text, what is the purpose of installing an equipment grounding conductor (EGC) with the supply circuit conductors?
To provide a path for equipment bonding.
According to the text, where should the impedance bonding jumper be connected?
At any point from the grounded side of the grounding impedance device to the equipment grounding connection at the service equipment or the first system disconnecting means
According to the text, what is the purpose of the grounding electrode conductor connection?
To connect the grounding electrode(s) to the building or structure disconnecting means
According to the text, how should the equipment bonding jumper be sized if the grounding electrode conductor connection is made at the grounding impedance device?
In accordance with 250
Which one of the following is NOT considered a grounding electrode according to the text?
Metal underground gas piping systems
What is the minimum diameter requirement for rod-type grounding electrodes made of stainless steel and copper or zinc-coated steel, unless listed?
15.87 mm (5/8 in.)
What is the minimum surface area requirement for plate electrodes made of bare or electrically conductive coated iron or steel plates?
0.186 m2 (2 ft2)
When is a supplemental electrode required to be installed in addition to a rod, pipe, or plate electrode?
When the resistance to earth of the grounding electrode is 25 ohms or less
Which one of the following is the correct sizing requirement for the common grounding electrode conductor?
The circular mil area of the largest ungrounded conductor(s) of each set of conductors that supplies the disconnecting means
When is the common grounding electrode conductor required to be installed?
For buildings or structures supplied by a feeder or branch circuit
What is the purpose of the common grounding electrode conductor?
To provide grounding for the service-entrance conductors
Which of the following is considered a grounding electrode system according to the text?
All of the above
What is the minimum diameter required for a bare or zinc galvanized rebar in a concrete-encased electrode?
13 mm (1/2 in.)
When is a concrete-encased electrode not required to be part of the grounding electrode system?
When the rebar is not accessible for use without disturbing the concrete
Which of the following is true regarding the bonding of metal in-ground support structures to the grounding electrode system?
Only one metal in-ground support structure needs to be bonded
Which one of the following materials is permitted for use as a grounding electrode conductor?
Copper or aluminum
When is it necessary to supplement a single rod, pipe, or plate electrode with a supplemental electrode?
When the electrode is used to supplement a metal underground water pipe-type electrode
What is the maximum size required for the bonding jumper that connects a supplemental grounding electrode to the grounded service enclosure?
6 AWG copper wire or 4 AWG aluminum or copper-clad aluminum wire
At what depth should a ground ring be installed below the surface of the earth?
750 mm (30 in.)
Which of the following is a requirement for grounding electrode conductors (GECs) installed in direct contact with concrete?
The GEC must be bare or covered without an extruded polymeric covering
Which type of grounding electrode conductor (GEC) is permitted to be in direct contact with concrete if installed within an enclosure listed for outdoor locations?
Aluminum GECs with an extruded polymeric covering
Which of the following materials can be used to protect a grounding electrode conductor (GEC) exposed to physical damage?
Rigid metal conduit (RMC)
Which of the following connections is permitted for splicing the wire-type grounding electrode conductor?
Riveted connection
Which one of the following is a method to measure the resistance to ground of a rod, pipe, or plate electrode?
Using a ground tester to measure the fall of potential between the rod being tested and a reference rod connected to the tester
According to the text, how should a rod or pipe electrode be installed to meet the requirements?
At least 2.44 m (8 ft) of length in contact with the soil and driven to a depth of not less than 2.44 m (8 ft)
According to the text, what is the spacing requirement for multiple auxiliary rod, pipe, or plate electrodes?
Not less than 1.83 m (6 ft) from any other electrode of another grounding system
According to the text, what is the requirement for bonding jumper(s) used to connect the grounding electrodes together?
Installed in accordance with 250.64(A), (B), and (E), sized in accordance with 250.66, and connected in the manner specified in 250.70
According to the text, how should the common grounding electrode conductor taps be sized?
Based on the size of the largest service-entrance or feeder conductor serving the individual enclosure
Which one of the following methods is NOT permitted for connecting the tap conductors to the common grounding electrode conductor?
Connections to an aluminum or copper busbar
What is the minimum size required for the common grounding electrode conductor for a separately derived system?
Based on the sum of the circular mil area of all the ungrounded conductors supplying the disconnecting means
Which of the following is a requirement for the bonding of metal raceways, enclosures, and cable armor for grounding electrode conductors?
The bonding jumper should be the same size as, or larger than, the largest enclosed grounding electrode conductor.
What is the purpose of the grounding electrode conductor(s) and bonding jumpers in the grounding electrode system?
To create an electrically parallel path between the grounding electrode(s) and the service equipment disconnecting means.
Which one of the following is a requirement for grounding electrode conductors (GECs) installed in direct contact with concrete?
The GEC should be bare.
When is a supplemental electrode required to be installed in addition to a rod, pipe, or plate electrode?
When the ground resistance is too high.
According to the text, what is the purpose of a rebar-type concrete-encased electrode?
To extend grounding and bonding conductor connections to the grounding electrode
According to the text, what is the purpose of the metal structural frame of a building in relation to grounding electrodes?
To act as a conductor to interconnect grounding electrodes
According to the text, when is interior metal water piping located more than 5 ft from the point of entrance to the building permitted to be used as a bonding conductor or grounding electrode conductor?
When the interior metal water pipe is located in an industrial, commercial, or institutional building
According to the text, what is the purpose of a ground clamp connected to a galvanized water pipe electrode?
To prevent galvanic corrosion
Which one of the following is the correct sizing requirement for the grounding electrode conductor and bonding jumper(s) for connection of grounding electrodes in an alternating-current system?
The size of the grounding electrode conductor and bonding jumper(s) shall not be smaller than given in Table 250.66.
Which one of the following is NOT considered a grounding electrode according to the text?
Metal enclosure
What is the maximum size required for the bonding jumper that connects a supplemental grounding electrode to the grounded service enclosure?
4 AWG aluminum or copper-clad aluminum wire
According to the text, what is the purpose of connecting the grounding electrode(s) to a busbar?
To accommodate the number of terminations necessary for the installation
According to the text, which of the following is NOT a permitted method for connecting the grounding or bonding conductor to the grounding electrode?
Solder connections
According to the text, which type of ground clamp is suitable for indoor communications systems?
Sheet metal strap-type ground clamp
According to the text, when is a metal enclosure or raceway for service conductors and equipment NOT required to be connected to the grounded conductor or grounding electrode conductor?
When isolated from possible contact by a minimum cover of 450 mm (18 in.)
According to the text, which of the following is NOT a requirement for metal enclosures and raceways for other than service conductors?
Connected to the equipment grounding conductor
Which one of the following is a requirement for connecting a grounding electrode conductor at the service equipment?
The mechanical elements used to terminate the grounding electrode conductor shall be accessible.
Which one of the following is NOT required to be accessible when terminating a grounding electrode conductor or bonding jumper to a grounding electrode?
Connections made to a metal underground water pipe electrode located not more than 1.52 m (5 ft) from the point of entrance to the building.
Which one of the following is a requirement for ensuring an effective grounding path when connecting a grounding electrode conductor or bonding jumper to a grounding electrode?
Bonding shall be provided around insulated joints and around any equipment likely to be disconnected for repairs or replacement.
Which one of the following is a location where grounding electrode conductors and bonding jumpers can be connected to extend the connection to an electrode(s)?
Interior metal water piping that is electrically continuous with a metal underground water pipe electrode and is located not more than 1.52 m (5 ft) from the point of entrance to the building.
Which one of the following is NOT a requirement for metal enclosures and raceways for other than service conductors?
They must be isolated from possible contact to any part of the metal components by being encased in concrete
According to the text, when is a common grounding electrode conductor permitted to be used for a separately derived system?
When the system is supplied by a generator with a grounded conductor
According to the text, which type of ground clamp is suitable for indoor communications systems?
Stainless steel ground clamp
Which one of the following is NOT considered a suitable method for ensuring electrical continuity at service equipment, service raceways, and service conductor enclosures?
Using standard locknuts or bushings
What is the purpose of bonding-type locknuts and grounding and bonding bushings for use with rigid or intermediate metal conduit?
To provide a reliable connection between the bushing and the conduit
When are grounding and bonding hubs suitable for bonding the conduit?
When they have been listed as grounding and bonding equipment per UL 467
What is the purpose of a listed split-type bond bushing used to connect a threaded conduit to an enclosure?
To provide the bonding connection required by 250.92(B)
According to the text, which of the following methods is permitted for bonding around pre-punched concentric or eccentric knockouts in an enclosure?
Threadless couplings and connectors for cables with metal sheaths
According to the text, how should expansion, expansion-deflection, or deflection fittings and telescoping sections of metal raceways be made electrically continuous?
By using equipment bonding jumpers
According to the text, which of the following is NOT a requirement for ensuring electrical continuity of normally non-current-carrying metal parts in hazardous (classified) locations?
Grounding electrodes
According to the text, what is the minimum size required for the supply-side bonding jumper in a single raceway or cable installation?
As specified in Table 250.102(C)(1)
Which one of the following is NOT a requirement for sizing the grounded conductor(s) in each raceway or cable according to the text?
Based on the size of the largest service-entrance conductor required for the load to be served
What is the minimum size required for the grounded conductor or bonding jumper when the circular mil area of ungrounded supply conductors connected in parallel is larger than 1100 kcmil copper or 1750 kcmil aluminum?
121/2 percent of the area of the largest ungrounded supply conductor or equivalent area for parallel supply conductors
What is the maximum length permitted for an equipment bonding jumper or supply-side bonding jumper installed on the outside of a raceway or enclosure?
1.8 m (6 ft)
What is the purpose of installing bonding jumpers or conductors and equipment bonding jumpers inside a raceway or an enclosure according to the text?
To provide grounding for the bonding jumpers or conductors themselves
Which one of the following is NOT a requirement for an intersystem bonding termination (IBT) according to the text?
Be securely mounted to a metal enclosure for the grounding electrode conductor with a minimum 6 AWG copper conductor
What is the purpose of an intersystem bonding termination (IBT) according to the text?
To minimize potential differences between equipment of different systems
In which locations should an intersystem bonding termination (IBT) be provided according to the text?
Both at the service equipment or metering equipment enclosure and at the disconnecting means for buildings or structures supplied by a feeder or branch circuit
When is the installation of an intersystem bonding termination (IBT) not required according to the text?
In existing buildings or structures where intersystem bonding and grounding electrode conductors exist
Which one of the following is a requirement for bonding nonmetallic raceways and enclosures to ensure electrical continuity and the capacity to conduct fault current likely to be imposed on them?
Removing any nonconductive coating at contact points
Which one of the following is a requirement for grounding equipment enclosures supplied by a branch circuit to reduce electromagnetic interference on the grounding circuit?
Installation of an internal insulated equipment grounding conductor
Which one of the following is a method to ensure electrical continuity of metal raceways and cables with metal sheaths that contain any conductor other than service conductors for circuits over 250 volts to ground?
Bonding to the grounded service equipment enclosure
Which one of the following is a requirement for connecting intersystem bonding conductors according to the text?
Connection to the grounding electrode system
Which one of the following is a requirement for bonding nonmetallic water pipe in a power system?
The bond must be connected to the power GEC or a metal service raceway
Which one of the following is a requirement for connecting intersystem bonding conductors in a building or structure?
The building or structure must have communications systems installed
What is the purpose of an intersystem bonding termination device?
To connect bonding jumpers or GECs in situations where suitable points are not available
Which one of the following is a requirement for bonding other enclosures in a power system?
Metal non-current-carrying parts must be bonded to ensure electrical continuity and the capacity to conduct fault current
Which one of the following is a requirement for grounding equipment enclosures supplied by a branch circuit to reduce electromagnetic interference on the grounding circuit?
If flexibility is necessary to minimize the transmission of vibration from equipment or to provide flexibility for equipment that requires movement after installation, a wire-type equipment grounding.
What is the purpose of the common grounding electrode conductor?
To connect the grounding electrode(s) to a busbar.
Which one of the following is NOT considered a grounding electrode according to the text?
Metal enclosure
Which of the following is NOT a requirement for grounding equipment enclosures described in 250.112(A) through (K)?
The equipment must be permanently mounted
In which of the following locations should electrical equipment be grounded, except for pendant lampholders supplied by circuits not over 150 volts to ground?
Commercial garages, theaters, and motion picture studios
Which of the following is a requirement for grounding equipment connected by cord and plug?
Exposed, normally non-current-carrying metal parts must be connected to the equipment grounding conductor
Which of the following is NOT a condition under which listed tools, appliances, and equipment covered in 250.114 are exempted from being connected to an equipment grounding conductor?
If operated in hazardous (classified) locations
Which one of the following is a requirement for the sizing of bonding jumpers to a metal water piping system, according to the text?
The bonding jumper must be larger than 3/0 AWG copper or 250 kcmil aluminum or copper-clad aluminum.
Which one of the following is NOT subject to the requirements of 250.104(A) for bonding to the grounding electrode system, according to the text?
Isolated sections of metal water piping connected to an overall nonmetallic water piping system.
What is the maximum size required for the bonding jumper that connects a supplemental grounding electrode to the grounded service enclosure, according to the text?
3/0 AWG copper or 250 kcmil aluminum or copper-clad aluminum.
Which type of equipment grounding conductor (EGC) is permitted to be used with circuit conductors protected by overcurrent devices rated at 20 amperes or less?
Copper-clad aluminum conductor
Which type of flexible metal conduit is required to have a wire-type equipment grounding conductor or bonding jumper installed if flexibility is necessary for equipment movement after installation?
Listed flexible metal conduit terminated in listed fittings
What is the maximum length allowed for the combined flexible metal conduit, flexible metallic tubing, and liquidtight flexible metal conduit in the same effective ground-fault current path?
1.8 m (6 ft)
What is the maximum metric designator (trade size) allowed for listed flexible metal conduit with circuit conductors protected by overcurrent devices rated at 20 amperes or less?
35
Which one of the following is NOT a requirement for bonding metal water piping systems in multiple-occupancy buildings according to the text?
Metal water piping system(s) shall be bonded to the building or structure disconnecting means enclosure
Which one of the following is a requirement for bonding other metal piping systems according to the text?
Bonding conductor(s) or jumper(s) shall be sized in accordance with Table 250.122
According to the text, what is the purpose of bonding all piping and metal air ducts within the premises?
To provide additional safety
According to the text, when is a supplemental electrode required to be installed in addition to a rod, pipe, or plate electrode?
When the grounding electrode system is installed in a building or structure supplied by a feeder or branch circuit
According to the text, when is a metal enclosure or raceway for service conductors and equipment NOT required to be connected to the grounded conductor or grounding electrode conductor?
When it is supplied by a wiring method that provides an equipment grounding conductor
According to the text, what is the purpose of an intersystem bonding termination device?
To bond the lightning protection system ground terminals to the building or structure grounding electrode system
According to the text, what is the maximum length permitted for an equipment bonding jumper or supply-side bonding jumper installed on the outside of a raceway or enclosure?
8 ft
According to the text, what is the purpose of fully insulating the impedance grounding conductor?
To prevent the flow of ground-fault current through the grounding electrode conductor
Which of the following is NOT a requirement for bonding exposed structural metal in a metal building frame?
Bonding to the disconnecting means for buildings or structures supplied by a feeder or branch circuit
What is the maximum size permitted for the bonding jumper(s) used to connect grounding electrodes together?
All of the above
When is a separate bonding jumper to the metal water piping system NOT required for a separately derived system?
All of the above
What is the sizing requirement for the bonding jumper(s) used to connect exposed structural metal to the grounded conductor of a separately derived system?
Both of the above
Test your knowledge on grounding requirements for vehicles and trailers with this quiz. Learn when the frame of a generator does not need to be connected to a grounding electrode, based on specific conditions.
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