Article 250 - Grounding and Bonding (Quarter 4)
Grounding electrodes of bare or electrically conductive coated iron or steel plates shall be least ______ in. thick.
1/4
Where rock bottom is encountered, a rod or pipe electrode shall be driven at an angle not to exceed __________ degrees from the vertical.
45
Grounding electrodes of the rod type less than _________ in diameter shall be listed.
5/8
Listed liquidtight flexible metal conduit (LFMC) is acceptable as an equipment grounding conductor when it terminates in listed fittings and is protected by an overcurrent device rated 60A or less for trade sizes 3/8 through 1/2. True or False
False
Local metal underground systems or structures such as underground tanks are permitted to serve as grounding electrode. True or False
True
Reinforcing bars for use as a concrete-encased electrode can be bonded together by the usual steel tie wires or other effective means. True or False
True
An equipment grounding conductor shall be identified by __________.
a continuous outer finish that is green, being bare, or a continuous outer finish that is green with one or more yellow stripes (any of these)
Where practicable, rod, pipe, and plate electrode shall be installed ______.
below permanent moisture level
Equipment grounding conductors, grounding electrode conductors, and bonding jumpers shall be connected by ____________________.
listed pressure connectors, terminal bars, and exothermic welding (any of these)
Ground clamps or other fittings exposed to physical damage shall be enclosed in _________________, or equivalent protective covering.
metal or wood
_________________ on equipment to be grounded or bonded shall be removed from contact surfaces to ensure good electrical continuity.
paint, lacquer, or enamel (any of these)
Swimming pool structures and structural _______ [680.26(B)(1) and (B)(2)] shall not be used as a grounding electrode.
reinforcing steel
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 burred in a trench that is at least ______ deep
30 in
An insulated or covered conductor _________ AWG and larger shall be permitted, at the time of installation, to be permanently identified as an equipment grounding conductor at each end and at every point where the conductor is accessible.
4
Rod and pipe grounding electrodes shall not be less than ________ ft in length.
8
A rod or pipe electrode shall be installed such that at least _________ of length is in contact with the soil.
8 ft
_______ shall not be used as grounding electrodes.
Metal underground gas piping systems and aluminum
Two or more grounding electrodes bonded together are considered a single grounding electrode system. True or False
True
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 _______________.
bare copper conductor not smaller than 4 AWG
A wire-type equipment grounding conductor installed in compliance with 250.6(A) and the applicable requirements for ______ in Parts II, III, and IV of Article 250 shall be permitted to serve as ___________.
both an equipment grounding conductor and a grounding electrode conductor
The structural metal frame of a __________ shall not be used as an equipment grounding conductor.
building or structure
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
Conductors with insulation or individual covering that is ______, or otherwise identified by this section shall not be used for ungrounded or grounded circuit conductors.
green or green with one or more yellow stripes
The Code requires the installation of an equipment grounding conductor of the wire type in ________. a. rigid metal conduit b. intermediate metal conduit c. electrical metallic tubing d. none of these
none of these
if a single rod, pipe, or ___________ grounding electrode has a resistance to earth of 25 ohms or less, the supplement electrode shall not be required.
plate
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
Unless part of a suitable Chapter 3 cable wiring method, equipment grounding conductors of bare or coveres copper-clad aluminum, shall not be installes where subject to corrosive conditions or be installed in direct contact with concrete, masonry, or the earth. True or False
true
Listed FMC and LFMC is permitted as an equipment grounding conductor at lengths _______ ft.
up to 6
Where a metal undergrounded water pipe is used as a grounding electrode, the continuity of the grounding path or the bonding connection to he interior piping shall not rely on ________ and similar equipment.
water meters or filtering devices
Type MC cable provides an effective ground-fault current path and is recognized by the NEC as an equipment grounding conductor __________.
when it contains an insulated or uninsulated equipment grounding conductor in compliance with 250.118(1)
exposed, normally non-current-carrying metal parts of cord-and-plug-connected equipment shall be connected to the equipment grounding conductor where operated at over __________ to ground.
150V
Concrete-encased grounding electrodes that are installed where the concrete is installed with _____________ is not considered to be in direct contact with the earth.
insulation, vapor barriers, or films (any of these)
A ground ring encircling the building or structure can be used as a grounding electrode when the ___________.
ring is in direct contact with the earth, ring consists of at least 20 ft of bare copper conductor, and bare copper conductor is not smaller than 2 AWG (all of these)
Listed FMC can be used as the equipment grounding conductor if the conduit does not exceed trade size ______________.
1 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
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
Listed FMC can be used as the equipment grounding conductor if the length in any ground return path does not exceed 6 ft and the circuit conductors contained in the conduit are protected by overcurrent devices rated at _____ or less.
20V
Where not routed with circuit conductors as permitted in 250.130(C) and 250.134(A) Exception No. 2, equipment grounding conductors smaller than _______ shall be protected from physical damage by an identified raceway or cable armor.
6 AWG
The upper end of a ground rod electrode shall be __________________ unless the above-ground end and the grounding electrode conductor attachment are protected against physical damage.
flush with or below ground level
One or more insulated conductors in a multi-conductor cable, at the time of installation, shall be permitted to be permanently identified as equipment grounding conductors at each end and at every point where the conductors are accessible by coloring the insulation _________.
green
A buried iron or steel plate used as a grounding electrode shall expose not less then ________ 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
Where the supplemental electrode is a rod, that portions of the bonding jumper that is the sole connection to the supplemental grounding electrode shall not be required to be larger than _______ AWG copper.
6
Where bonding jumpers are used to connect grounding electrodes together to form a grounding electrode system, rebar is permitted to be used as a conductor to interconnect the electrodes. True or False
False
The armor of Type AC cable is recognized by the NEC as an equipment grounding conductor. True or False
True
