Grounding and Bonding Review
If a 400-ampere service is grounded by connection to a single ground rod, what is the maximum-size grounding electrode conductor required?
6 AWG copper
The _____ is not permitted to be connected to normally non-current-carrying metal parts of equipment, to equipment grounding conductors, or be reconnected to ground on the load side of the service disconnecting means except as otherwise specifically permitted in Article 250.
Grounded conductor (usually neutral)
The ? is the conductive object directly connected to earth through which grounding is established.
Grounding Electrode
The total opposition to current in an AC circuit is known as circuit ? .
Impedance
The opposition to current in a DC circuit is ? .
Resistance
If a conductive part is connected to the ground or to a conductive body that extends a ground connection, it is ? .
Grounded
The NEC generally requires ________ to be installed with feeders and branch circuits
Equipment grounded conductor
A(n) ? occurs when electrical current in a circuit returns through the equipment grounding conductor (EGC), through a conductive material such as the electrical system ground (metal, water pipes, and so forth), through a person, or through a combination of these ground return paths.
Ground fault
An unintentional, electrically conducting connection between the ungrounded conductor of an electrical circuit and the normally non-current-carrying conductors, metallic enclosures, metallic raceways, metallic equipment, or earth best defines which of the following?
Ground fault
In an ungrounded system, equipment grounding is accomplished through the required connection of the feeder or branch circuit equipment grounding conductor(s) to the ? .
Grounding electrode conductor
What three things are accomplished through electrical bonding?
1. Conductivity 2. Connecting together 3. Continuity
Two basic concepts of Grounding
1. Grounding of equipment 2. Grounding of systems
Electrical systems that are grounded shall be connected to earth to provide the following functions (Three)
1. Limit line surges, or unintentional contact with lines of higher voltage 2. Limit the voltage imposed by lightning 3. Stabilize voltages during normal operation
Bonding
1. minimizes potential differences between conductive parts that are bonded together 2. safeguards against shock hazards 3. ensures an effective path for ground-fault current.
A conductive body that extends the ground connection (Three)
1.Equipment bonding jumper 2. Equipment grounding conductor 3. Grounding Electrode conductor
Service entrance conductor size 500 kcmill What is the minimum-size copper grounding electrode conductor required for this service
1/0 AWG (use table 250.66)
4/0 AWG copper service entrance conductor What is the minimum size copper grounding electrode conductor required for this service?
2 AWG
What is the minimum size for equipment sized grounding conductor?
2 AWG
If ungrounded service is 1000 kcmill, the minimum supply side jumper size is __________
2/0
Single steel plate, rod, and pipe the maximum resistance when tested should not be greater than_________
25 ohms
Wire-type equipment grounding conductors expressed in Table 250.122 of the NEC are approximately ? of the circuit conductor size.
25%
What is the minimum size copper bonding conductor for an interior metal water piping system if the building is supplied by a service that has a large ungrounded service entrance conductor size of 2,500 kcmil
3/0 AWG
What is the minimum length of the ground rod type electrode for telecommunications depth?
5 ft
Equipment grounding conductors installed with medium-voltage cables are generally required to be sized based on Table 250.122 and are never smaller than ? copper.
6 AWG
If the voltage of a circuit is 240 volts and the resistance of the circuit is 30 ohms, how much current would be present in the circuit?
8A
A grounding electrode connection is required to be made at an _________ location anywhere from the load end of the overhead service conductors, Service drop, Underground Service conductors, or service lateral up to and including the terminal or bus to which the grounded conductor is connected in the service disconnecting means
Accessible
In order for the grounded conductor to connect two separate structures, there may not be
Continuous metallic paths
If resistance is lowered, what happens to current or I
Current increases
In order for an electrode to qualify, the grounding electrode has to have ____________ to ground
Direct connection
Listed equipment protected by a system of _______________, or its equivalent, shall not be required to be connected to the equipment grounding conductor. Where such a system is employed, the equipment shall be distinctively marked
Double insulation
In a grounded system, normally non-current-carrying electrically conductive materials that are likely to become energized, such as building metal framing and metal water piping, shall be connected together and to the electrical supply source in a manner that establishes an ___?____
Effective ground fault current path
For grounding systems, normally concurrent-carrying conductor materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected together and to the ______ to establish an effective ground-fault current path.
Electrical supply source
A(n) ? is generally required to connect the grounding terminal of a grounding-type receptacle to a grounded box.
Equipment bonding jumper
The connection between 2 or more portions of a grounding equipment conductor is called __?__
Equipment bonding jumpers
Electrical systems that are grounded do NOT
Facilitate overcurrent device operation
Which part of Article 250 provides specific electrical bonding requirements?
Part V
Equipment must have a ______________ rating equal to or greater than the amount of available fault current
Short-Circuit current
Where a feeder supplies a separate building or structure, and an interconnected metal frame of that structure must be bonded, what NEC table is used to size the bonding jumper?
Table 250.102(C)(1
The minimum size required for a supply-side bonding jumper is provided in which of the following NECtables?
Table 250.102(C)(1)
What table is required to be used for sizing the right jumper for a structural metal frame?
Table 250.102(C)(1)
Which NEC table provides information about sizing wire-type equipment grounding conductors?
Table 250.122
Which NEC table provides the minimum sizes for wire-type equipment grounding conductors?
Table 250.122
What is the purpose of the grounding electrode?
The purpose of a grounding electrode is to function as the connection between the ground (Earth) and grounded electrical systems and electrical equipment.
The practical safeguarding of persons and property from hazards arising from the use of electricity best describes which of the following?
The purpose of the NEC
In a grounded electrical system, the grounded conductor of the system is forced to take on _____ the ground (earth).
The same potential as
What is property and persons being protected from per the NEC code?
The use of electricity
Which conductors should be identified as green or green with yellow stripes?
Wire type grounded conductors
Which materials are permitted as a wire-type grounding electrode conductor?
a. Aluminum b. Copper c. Copper-clad aluminum **Steel is not permitted
Which of the following functions are performed by an equipment grounding conductor (EGC)?
a. Bonding b. Creating an effective ground-fault current path c. Grounding of equipment **All of the above**
If the Code provides a requirement to ground equipment, it generally implies that there will be either a direct connection to the earth or a connection to ground through which of the following?
a. Equipment grounding conductor b. Grounding electrode c. Grounding electrode conductor **Any of the above**
Characteristics of an effective ground-fault current path
a. Intentionally constructed b. Low-impedance electrically conductive path c. Designed and intended to carry current during ground-fault conditions **All of the above**
