Specifications

NAIROBI OPERATIONAL HUB
UNOPS Building, UN Lane, Off UN Avenue Tel: [phone]
P.O Box 783,Village Market, 00621 E-mail: [e-mail]
Nairobi, Kenya Website: www.unops.org
UNOPS is ISO 9001 certified
F. Changes in direction of duct bank runs shall be accomplished by using special
couplings limited to 5 degrees and/or 45 degrees bends having a 1 m radius sweep
with straight sections of ducts between changes of direction and `S' sweep sections
having a minimum of 500 m offset.
G. Where duct bank enters manholes, conduits shall terminate in end bells. Clean each
conduit thoroughly before laying. During construction and after completion of the
duct banks, plug the ends of conduits to prevent water washing mud into the
conduits. Take particular care to keep the conduits clean of concrete or any other
substance during the course of construction.
H. Securely anchor duct and brace with intermediate and base plastic spacers to prevent
movement during the placement of concrete.
K. After the completion of portion of duct bank, a mandrel not less than 300 mm long,
with a diameter of approximately 6 mm less than the inside nominal diameter of the
conduits shall be pulled through each conduit, after which a brush with stiff bristles
shall be pulled through to make certain that no particles of earth, sand or gravel have
been left in the line. This cleaning shall be done one day after the concrete has been
poured.
L. Install a nylon rope in each conduit after cleaning, after which the conduits shall be
capped/plugged immediately.
M. All duct banks shall enter manholes through rectangular openings of suitable
dimensions provided in walls. Such holes shall be sized to properly receive the
duct, but shall not be too large for proper caulking. The space between duct banks
and manhole walls shall be caulked tight with lead wool.
3.04 STUB-UPS INSTALLATION
A. Comply with relevant requirement of Section 16130.
B. Exact stub-ups locations and termination requirements for each equipment shall be
verified on site, before commencement of laying underground or under floor PVC
conduits for required power and control wiring.
C. Where extensions of PVC conduits above grade are required as stub-ups, a
transition bend having PVC/Steel coupling on one end and threaded male or female
adapter on the other end shall be used.