B&G Chapter 2 Parts III, IV and V Review Questions

Bonding jumper(s) from grounding electrode(s) shall be permitted to be connected to an aluminum or copper busbar not less than _____ and of sufficient length to accommodate the number of terminations necessary for the installation in accordance with 250.64(F).

1/4 in. thick × 2 in. wide

In order for a metal underground water pipe to be used as a grounding electrode, it shall be in direct contact with the earth for _____.

10 ft or more

Where used outside, aluminum or copper-clad aluminum grounding electrode conductors shall not be terminated within _____ in. of the earth.

18

A buried iron or steel plate used as a grounding electrode shall expose not less than _____ sq ft of surface area to exterior soil.

2

A bare 4 AWG copper conductor installed horizontally near the bottom or vertically, and within that portion of a concrete foundation or footing that is in direct contact with the earth, can be used as a grounding electrode when the conductor is at least _____ ft in length.

20

The largest size grounding electrode conductor required is _____ copper.

3/0 AWG

When a ground ring is used as a grounding electrode, it shall be installed at a depth below the earth's surface of not less than _____.

30 in.

Where rock bottom is encountered when driving a ground rod at an angle up to 45 degrees, the electrode can be buried in a trench that is at least _____ deep.

30 in.

Grounding electrode conductors _____ AWG and larger that are not exposed to physical damage can be run along the surface of the building construction without metal covering or protection.

6

Grounding electrode conductors smaller than _____ AWG shall be protected in rigid metal conduit, IMC, PVC conduit, electrical metallic tubing, or cable armor.

6

Where the supplemental electrode is a rod, that portion of the bonding jumper that is the sole connection to the supplemental grounding electrode shall not be required to be larger than _____ AWG copper wire.

6

Ground rod electrodes shall be installed so that at least _____ of the length is in contact with the soil.

8 ft

Grounding electrode conductors shall be installed in one continuous length without a splice or joint, unless spliced by _____.

Any of these - connecting together sections of a busbar - irreversible compression-type connectors listed as grounding and bonding equipment - the exothermic welding process

The grounding conductor connection to the grounding electrode shall be made by _____.

Any of these - listed lugs - exothermic welding - listed pressure connectors

An electrode encased by at least 2 in. of concrete, located horizontally near the bottom or vertically and within that portion of a concrete foundation or footing that is in direct contact with the earth, shall be permitted as a grounding electrode when it consists of _____.

a OR b - at least 20 ft of 1/2 in. or larger steel reinforcing bars or rods - at least 20 ft of bare copper conductor of 4 AWG or larger

Where practicable, rod, pipe, and plate electrodes shall be installed _____.

below permanent moisture level

Ferrous metal raceways and enclosures for grounding electrode conductors shall be bonded at each end of the raceway or enclosure to the grounding electrode or grounding electrode conductor to create a(n) _____ parallel path.

electrically

Auxiliary grounding electrodes can be connected to the _____.

equipment grounding conductor

Concrete-encased electrodes of _____ shall not be required to be part of the grounding electrode system where the steel reinforcing bars or rods aren't accessible for use without disturbing the concrete.

existing buildings or structures

Buildings or structures supplied by multiple services or feeders shall use the same _____ to ground enclosures and equipment in or on that building.

grounding electrode system

Bare aluminum or copper-clad aluminum grounding electrode conductors shall not be used where in direct contact with _____ or where subject to corrosive conditions.

masonry or the earth

Swimming pool structures and structural _____ [680.26(B)(1) and (B)(2)] shall not be used as a grounding electrode.

reinforcing steel

Grounding electrode conductors and grounding electrode bonding jumpers in contact with _____ shall not be required to comply with 300.5, but shall be buried or otherwise protected if subject to physical damage.

the earth

Where the resistance-to-ground of 25 ohms or less is not achieved for a single rod electrode, _____.

the single rod electrode shall be supplemented by one additional electrode

If a building or structure is supplied by a service or feeder with _____ or more disconnecting means in separate enclosures, the grounding electrode connections shall be made in accordance with 250.64(D)(1), 250.64(D)(2), or 250.64(D)(3).

two

Grounding electrodes of the rod type less than _____ in diameter shall be listed.

5/8 in.

Local metal underground systems or structures such as _____ are permitted to serve as grounding electrodes.

All of these - piping systems - underground tanks - underground metal well casings that are not bonded to a metal water pipe

Grounding electrodes of bare or electrically conductive coated iron or steel plates shall be at least _____ in. thick.

1/4

One or more metal in-ground support structure(s) in direct contact with the earth vertically for _____ ft or more, with or without concrete en-casement is permitted to be a grounding electrode in accordance with 250.52.

10

What size copper grounding electrode conductor is required for a service that has three sets of 600 kcmil copper conductors per phase?

3/0 AWG

In an ac system, if the size of the grounding electrode conductor or bonding jumper connected to a concrete-encased electrode does not extend on to other types of electrodes that require a larger size of conductor, the grounding electrode conductor shall not be required to be larger than _____ AWG copper.

4

Interior metal water piping that is electrically continuous with a metal underground water pipe electrode and is located more than _____ ft from the point of entrance to the building shall not be used as a conductor to interconnect electrodes of the grounding electrode system.

5

Where conditions of maintenance and supervision ensure only qualified persons service the installation in _____ buildings, the entire length of the metal water piping system can be used for grounding purposes, provided the entire length, other than short sections passing through walls, floors, or ceilings, is exposed.

All of these - industrial - institutional - commercial

If the grounding electrode conductor or bonding jumper connected to a single or multiple rod, pipe, or plate electrode(s), or any combination thereof, as described in 250.52(A)(5) or (A)(7), does not extend on to other types of electrodes that require a larger size conductor, the grounding electrode conductor shall not be required to be larger than _____ AWG copper wire.

6