storing explosives, ammunition, or explosive ingredients shall be a minimum
of 600 mm 2 feet above the ridge parapet, ventilator or perimeter. On open
or hooded vents emitting explosive dusts or vapors under natural or forced
draft, air terminals shall be a minimum of 1.5 m 5 feet above the opening.
On open stacks emitting explosive dusts, gases, or vapor under forced
draft, air terminals shall extend a minimum of 4.5 m 15 feet above vent
opening. Air terminals more than 600 mm 24 inches in length shall be
supported by a suitable brace, with guides not less than one-half the
height of the terminal.
2.1.4
Ground Rods
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NOTE: Designer will determine type and number of
ground rods to be used; based on local conditions,
earth resistivity data, and on the size and type of
the electrical installation. Copper clad steel rods
will be specified for normal conditions. Galvanized
coated steel or stainless steel rods will be used
where low soil resistivities are encountered and
galvanic corrosion may occur between adjacent
underground metallic masses and the copper-clad
rods. Stainless steel rods have a longer life than
the zinc coated steel, but use must be justified
based on the higher cost. In high resistivity
soils, 3.048 m (10 foot) sectional rods may be used
to obtain the required resistance to ground; however
where rock is encountered, additional rods, a
counterpoise, or ground grid may be necessary.
Coordinate and standardize rod selection for
individual facilities with other specification
sections.
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Rods made of [copper-clad steel] [stainless steel] [solid copper] shall
conform to UL 467 and galvanized ferrous rods shall conform to ANSI C135.30.
Ground rods shall be not less than 19.1 mm 3/4 inch in diameter and 3.048
m 10 feet in length. Ground rods of copper-clad steel, stainless steel,
galvanized ferrous, and solid copper shall not be mixed on the job.
2.1.5
Connectors
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NOTE: The bracketed area in this paragraph is only
required on Air Force projects which have a facility
which manufactures. processes, handles or stores
explosives, ammunition or explosive ingredients.
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Clamp-type connectors for splicing conductors shall conform to UL 96, class
as applicable, and, Class 2, style and size as required for the
installation. [Clamp-type connectors shall only be used for the connection
of the roof conductor to the air terminal and to the guttering. All other
connections, bonds, and splices shall be done by exothermic welds or by
high compression fittings. The exothermic welds and high compression
fittings shall be listed for the purpose. The high compression fittings
shall be the type which require a hydraulically operated mechanism to apply
a minimum of 10,000 psi.]
SECTION 13100A
Page 7
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