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[Each medium-voltage cable and conductor in manholes shall be fire-proofed
for their entire length within the manhole. Where cables and conductors
have been lubricated to enhance pulling into ducts, the lubricant shall be
removed from cables and conductors exposed in the manhole before
fireproofing.] [Fire-stops shall be installed in each conduit entering or
leaving a manhole.]
3.4.1
Tape Method
Before application of fireproofing tape, plastic tape wrapping shall be
applied over exposed metallic items such as the cable ground wire, metallic
outer covering, or armor to minimize the possibility of corrosion from the
fireproofing materials and moisture. Before applying fireproofing tape,
irregularities of cables, such as at cable joints, shall be evened out with
insulation putty. A flexible conformable polymeric elastomer fireproof
tape shall be wrapped tightly around each cable spirally in 1/2 lapped
wrapping or in 2 butt-jointed wrappings with the second wrapping covering
the joints of the first.
3.4.2
Sprayable Method
Manholes shall be power ventilated until coatings are dry and dewatered and
the coatings are cured. Ventilation requirements shall be in accordance
with the manufacturer's instruction, but not less than 10 air changes per
hour shall be provided. Cable coatings shall be applied by spray, brush,
or glove to a wet film thickness that reduces to the dry film thickness
approved for fireproofing by FM P7825a. Application methods and necessary
safety precautions shall be in accordance with the manufacturers
instructions. After application, cable coatings shall be dry to the touch
in 1 to 2 hours and fully cured in 48 hours, except where the manufacturer
has stated that because of unusual humidity or temperature, longer periods
may be necessary.
3.5
DUCT LINES
3.5.1
Requirements
Numbers and sizes of ducts shall be as indicated. Duct lines shall be laid
with a minimum slope of 100 mm per 30 m 4 inches per 100 feet. Depending
on the contour of the finished grade, the high-point may be at a terminal,
a manhole, a handhole, or between manholes or handholes. Short-radius
manufactured 90-degree duct bends may be used only for pole or equipment
risers, unless specifically indicated as acceptable. The minimum
manufactured bend radius shall be 450 mm 18 inches for ducts of less than
80 mm 3 inch diameter, and 900 mm 36 inches for ducts 80 mm 3 inches or
greater in diameter. Otherwise, long sweep bends having a minimum radius
of 7.6 m 25 feet shall be used for a change of direction of more than 5
degrees, either horizontally or vertically. Both curved and straight
sections may be used to form long sweep bends, but the maximum curve used
shall be 30 degrees and manufactured bends shall be used. Ducts shall be
provided with end bells whenever duct lines terminate in manholes or
handholes.
3.5.2
Treatment
Ducts shall be kept clean of concrete, dirt, or foreign substances during
construction. Field cuts requiring tapers shall be made with proper tools
SECTION 16375A
Page 54
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