Lesson 5: Grounding Electrode Conductors
Referring to the drawing, what is the minimum-size copper grounding electrode conductor required for this service?
1/0 AWG
An aluminum or copper-clad aluminum grounding electrode conductor that is installed external to buildings or equipment is not permitted to be connected to a grounding electrode at a distance less than ? from the earth.
18"
The minimum-size grounding electrode conductor required for a ring-type electrode is not less than ? .
2 AWG copper
What is the maximum size copper grounding electrode conductor required for a 6,000-ampere service supplied by ten 750 kcmil copper service conductors in parallel for each ungrounded service entrance phase conductor?
3/0 AWG copper
Where a metal underground water pipe is used as a grounding electrode, if the grounding electrode conductor is a 3/0 AWG copper, what is the minimum size required for the required bonding jumper around any water meters, filtering equipment, or similar equipment?
3/0 AWG copper
What is the largest size required for a copper grounding electrode conductor that is connected only to a concrete-encased electrode?
4 AWG copper
A single grounding electrode conductor installed in a ferrous metal raceway must not exceed ? of the cross-sectional area of the raceway.
53%
All grounding electrode conductors in sizes smaller than ? must be protected from physical damage by installation in raceway or cable armor.
6 AWG
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
What is the largest size required for a copper grounding electrode conductor that is connected only to a rod, pipe, or plate electrode?
6 AWG copper
Grounding electrode conductors smaller than 6 AWG shall be protected by installation in all but which of the following wiring methods?
FMT
Table 250.66 is used only for sizing grounding electrode conductors for alternating current services.
False
When using the common grounding electrode conductor tap method for grounding services with separate disconnecting means enclosures, the minimum size required for the common grounding electrode conductor is not less than 3/0 AWG copper or 250 kcmil aluminum.
False
Which NEC table is used for sizing grounding electrode conductors and bonding jumpers between electrodes in the grounding electrode system?
Table 250.66
Grounding electrode conductors must not be installed in lengths longer than ? .
There is no length restriction in the NEC; it is a design issue.
A grounding electrode conductor connects a system grounded conductor or equipment, or both, to a grounding electrode, or to a point on the grounding electrode system.
True
A grounding electrode conductor installed in a nonferrous metal raceway (such as aluminum conduit) is not required to be bonded to both ends of the raceway where it enters and emerges from the raceway.
True
Grounding electrode conductors are generally required to be installed without a splice or joint.
True
Grounding electrode conductors in sizes 6 AWG or larger must generally be protected where installed in locations where they are exposed to physical damage.
True
If a grounding electrode conductor is protected from physical damage with PVC conduit, the conduit is required to be Schedule 80.
True
Protection for grounding electrode conductors can be achieved by using schedule 80 PVC in construction that is not fire rated.
True
Where a metal underground water pipe is used as a grounding electrode, a bonding jumper is required for electrical continuity around any water meters, filtering equipment, or similar equipment.
True
A grounding electrode conductor is a conductive body that extends the grounding connection.
True
A single grounding electrode conductor connected to the grounding electrode system is permitted for a service, or individual grounding electrode conductors are permitted to be run from each electrode to the service equipment enclosure.
True
The interconnected metal structural frame of a building shall be permitted to be used as a conductor to interconnect electrodes of the grounding electrode system, or it is permitted to be used as a grounding electrode conductor.
True
Where a grounding electrode conductor for a 4,000-ampere service is connected only to two ground rod electrodes, the grounding electrode conductor is not required to be larger than 6 AWG copper.
True
Where a grounding electrode conductor is installed in a ferrous metal raceway that is not electrically continuous from the service cabinet to the grounding electrode, it must be made electrically continuous by bonding the contained grounding electrode conductor to both ends of the raceway.
True
More than one grounding electrode conductor is not permitted to be connected to a grounding electrode using a single clamp, unless the single clamp is ? for use with multiple conductors.
listed
A 6 AWG or larger copper grounding electrode conductor that is exposed to physical damage shall be protected by any of the following except ? .
reinforced thermosetting resin conduit (RTRC)
When installing grounding electrode conductor taps from a common grounding electrode conductor to each separate service disconnecting means enclosure, the minimum size required for the grounding electrode conductor taps is based on the ? .
size of the largest ungrounded service conductor in each enclosure using Table 250.66
Aluminum or copper-clad aluminum grounding electrode conductors are permitted within ? of the earth where installed in the bottom of an electrical enclosure that is listed for the environment.
1. 6" 2. 12" 3. 18"
If the DC system (source) is located on the premises, the grounding electrode conductor connection is required to be made at which of the following locations?
1. At the first system disconnecting means or overcurrent protective device 2. At the source 3. By other means that provides equivalent protection and utilizes listed and identified equipment
Grounding electrode conductor connections are required to be accessible in all but which of the following locations?
1. Buried electrode connections 2. Concrete-encased electrodes 3. Exothermic welding connections to building steel under fire-proofing material
Referring to the drawing, what is the minimum size copper grounding electrode conductor required for this service?
2 AWG
A grounding electrode conductor installed for a communications system is required to be sized using NEC Table 250.66.
False
Grounding electrode conductors and grounding electrode bonding jumpers in contact with the earth must comply with the burial depths in Table 300.5.
False
The amount of current present in a grounding electrode conductor during normal system operation is low because the earth is a(n) ? conductor and a high-impedance path for current.
Poor
Which of the following nonmetallic raceways is recognized in the NEC for protection of grounding electrode conductors from physical damage?
Schedule 80 PVC
Which of the following materials is not permitted as a wire-type grounding electrode conductor?
Steel
Grounding electrode conductor connections are required to be made using any but which of the following?
V. Sheet metal screws VII. Wrapping the conductor around the nut and bolt connection
Grounding electrode conductors are permitted to have which of the following physical characteristics?
1. Bare 2. Covering 3. Insulation
Where a splice is made in a grounding electrode conductor(s), which of the following methods are permitted?
1. Exothermic welding 2. Irreversible compression connections 3. Splices on busbars
If a service is supplied by 4/0 AWG copper ungrounded service-entrance conductors, what is the minimum-size grounding electrode conductor required for a metal underground water pipe electrode?
2 AWG copper
Grounding electrode conductors are not permitted to be installed by routing them through metal framing members.
False
Where a length of reinforcing rod (rebar) is used as a concrete-encased electrode, rebar extensions that exit from the concrete shall be permitted to be exposed to the earth without the use of corrosion protection.
False
