couplings at low temperatures, such couplings shall not be installed when
temperatures are below minus 18 degrees C (0 degrees F). 0 degrees F.
Couplings shall be warmed in hot water or by another approved method when
installed at temperatures below 0 degrees C (32 degrees F). 32 degrees F.
3.5.5.2
Plastic Duct
Duct joints shall be made by brushing a plastic solvent cement on insides
of plastic coupling fittings and on outsides of duct ends. Each duct and
fitting shall then be slipped together with a quick one-quarter-turn twist
to set the joint tightly.
3.6
MANHOLES AND HANDHOLES
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NOTE: When preparing Section 16375A, ELECTRICAL
DISTRIBUTION SYSTEM, UNDERGROUND for a project
specification, the designer will edit the guide
specification as necessary to suit the specific
helipad installation. Note that for helipads
standard type manholes, vaults, manholes, vaults,
handholes, and their associated frames and covers
may be used. If one of these will be located on the
helipad or surface subject to aircraft traffic
loads, these features may require a design for a
maximum single wheel load of 22,680 kg (50,000
pounds) or dual wheel load of 40,820 kg (90,000
pounds). Use steel conforming to ASTM A 36,
"Structural Steel", for covers at helipad manholes,
vaults, and handholes. Use ductile iron for frames
conforming to ASTM A 536, grade 65-45-12.
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Manholes and handholes shall be as specified in Section 16375A ELECTRICAL
DISTRIBUTION SYSTEM, UNDERGROUND.
3.7
WELDING
The welding supports and metallic ducts and welding or brazing of
electrical connections shall be by qualified welders.
3.8
CABLE MARKERS
Cable markers or tags shall be provided for each cable at duct entrances
entering or leaving manholes or handholes and at each termination within
the lighting vault. Tag cables in each manhole or handhole with not less
than two tags per cable, one near each duct entrance hole. Immediately
after cable installation, tags shall be attached to cables and wires so
that they cannot be accidentally detached.
3.9
FRANGIBLE REQUIREMENTS
Frangible supports, couplings, and adapters shall be installed as indicated
or as specified.
3.10
ELEVATED HELIPAD LIGHTS
Elevated helipad lights shall be frangibly mounted, normally not exceeding
350 mm 14 inches in height, unless higher mounting is permitted in snow
SECTION 16525A
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