cables without a nonmetallic protective covering over the sheath or armor
prior to application of fireproofing. Wrap shall be in the form of two
tightly applied half-lapped layers of a pressure-sensitive 0.254 mm 10 mil
thick plastic tape, and shall extend not less than 25 mm one inch into the
duct. Even out irregularities of the cable, such as at splices, with
insulation putty before applying tape.
]3.1.16
Grounding Systems
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NOTE: For LANTNAVFACENGCOM projects, use the first
bracketed paragraph. Designer must determine the
grounding requirements for each project. Show all
necessary ground rods, ground girdles, etc., on the
drawings. For Communications - Electronic
facilities, specify a maximum resistance to ground
of 10 ohms (required by MIL-STD-188-124A).
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[Noncurrent-carrying metallic parts associated with electrical equipment
shall have a maximum resistance to solid earth ground not exceeding the
following values:
[Generating and control equipment 1000 volts and over:
1 ohm]
[Main substations] [, distribution substations] [, switching stations]
[, primary distribution stations enclosed by fences]:
[500 kVA or less:
5 ohms]
[500 kVA to 1000 kVA:
5 ohms]
[1000 kVA or over:
3 ohms]
[Pad-mounted transformers without protective fences:
5 ohms]
[Ground in manholes, handholes, and vaults:
5 ohms]
[Grounding other metal enclosures of primary voltage electrical and
electrically-operated equipment: 5 ohms]
[Grounded secondary distribution system neutral and
noncurrent-carrying metal parts associated with distribution
systems and grounds not otherwise covered: 5 ohms]
When work in addition to that indicated or specified is directed in order
to obtain the specified ground resistance, the provisions of the contract
covering "Changes" shall apply.]
[Shall be as indicated, and as required by NFPA 70 and ANSI C2.]
3.1.16.1
Grounding Electrodes
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NOTE: In areas of extremely high chemical activity
of soil, ground rods and other metals must not be
placed in direct contact with soil. Ground rods
shall be completely encased in concrete and
connections made to them by thermit welds. Chemical
isolation from soil shall be maintained to a point
at least 100 mm 4 inches above finished grade. When
SECTION 16302N
Page 36
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