NOTE: The designer will investigate soil
resistivity and other factors in accordance with
IEEE Std 80 and will specify and detail the
grounding in accordance with TM 5-811-1/AFM 88-9
Chapter 1 and IEEE Std 80.
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A grounding grid, consisting of the indicated configuration of bare copper
conductors and driven ground rods shall be installed as shown on the
drawings. Grounding grid shall comply with IEEE Std 80. Equipment frames
of metal-enclosed equipment, medium-voltage cable terminations, chain-link
fencing, metal-structures, and other noncurrent-carrying metal items shall
be connected to the ground grid as shown. At least two connections shall
be provided from [a power transformer,] [a switchgear ground bus,] [an oil
circuit breaker enclosure,] [and] [a grounded iron platform plate] to the
ground grid. Fences shall be grounded at each fixed gate post, each corner
post, and at intermediate posts as indicated. Each gate section shall be
bonded to its gate posts with a 3.2 x 25.4 mm 1/8 x 1 inch flexible braided
copper strap and ground post clamps. Fence ground clamps shall be of a
type that inhibits corrosion between metal parts. Outriggers shall be
grounded as shown.
3.4.1
Grounding Electrodes
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NOTE: Modify and/or delete paragraphs in accordance
with project requirements.
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Grounding electrodes shall be as follows:
a.
Driven rod electrodes - Unless otherwise indicated, ground rods
shall be driven into the earth until the tops of the rods are
approximately one foot below finished grade.
b.
Grid grounding electrodes - A grid grounding electrode shall be
installed as shown consisting of bare copper conductors installed
[300 mm] [450 mm] [600 mm] [12] [18] [24] inches, plus or minus 75
mm 3 inches, below the finished top of soil grade. Grid
conductors shall be bonded to all rod electrodes, and to all other
intersecting grid conductors. Grid conductors shall be sized as
shown.
3.4.2
Grounding and Bonding Connections
Connections above grade shall be made by the fusion-welding process or with
bolted solderless connectors, in compliance with UL 467, and those below
grade shall be made by the fusion-welding process. Where grounding
conductors are connected to aluminum-composition conductors, specially
treated or lined copper-to-aluminum connectors suitable for this purpose
shall be used.
3.4.3
Grounding and Bonding Conductors
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NOTE: Grounding and bonding conductors will be
sized based on the thermal requirements of IEEE Std
80.
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SECTION 16311A
Page 72
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