ANSI/NEIS 605:2005 pdf download.Installing Underground Nonmetallic Utility Duct.
a) To provide adequate dissipation of heat from cables within the duct
b) To provide void space to allow concrete to fully surround each duct
C) To physically separate ducts in the event of an electrical fault
4.3 Communication Duct Banks
Since there is no heat build-up in communications duct banks, separation is needed only to allow concrete to fully surround each duct.
4.4 Combined Power and Communications Duct
Many specifications require three inches or more of separation between power duct groups and communications duct groups. Since spacer manufacturers generally do not stock spacers larger than three-inches, a dummy spacer can he inserted horizontally between the power and communications to provide larger separations.
4.5 Considerations for Specifiers Frequently, duct bank designers speci’ center-to- center dimensions between ducts, leaving the contractor with the responsibility to calculate the clear dimensions. Standard spacer sizes are 1-inch, 1-1/2- inch, 2-inch, and 3-inch separation for power ducts. For any other separation, custom-produced spacers are required.
5.2.1 Bulk Storage
t.oose duct should be stacked parallel. To avoid excessive ovality on the bottom row, limit the stacking height to four feet for ER, five feet for DR duct, and 10 feet for RTRC. The bottom row of duct should be laid on as level a surface as possible. l)o not place supports under the duct, since this may cause excessive deflection and sagging.
5.2.2 Bends and Sweeps
Rends and sweeps can be stored outdoors on flat ground. Consult the manufacturer for other storage procedures.
5.2.3 Fittings, Spacers, and Accessories
%‘hen stored outdoors, fittings, spacers, and accessories in cartons should be under cover to protect cartons from the elements.
5.2.4 Cleaners, Primers, Cements, and Adhesives
Store all cleaners, primers, cements, and adhesives in a cool place except when actually in use at the job site. Do not store in freezing areas as this can cause premature gelation and loss of the cements. Some products have a limited shelf life when not stored in hermetically sealed containers. Consult the product manufacturer for specific recommendations on storage conditions and shelf life. In hermetically sealed containers, the normal shelf life of these products is approximately one to two years.
NOTE—Sonic products are flarnniable. Fumes can be har,nful if adequate ventilation is not provided.
5.2.5 Inventories
Inventories should he rotated—first in, first out—to minimize possible loss from excessive storage time.
2. Where required by regulations or by soil conditions, trench walls should be adequately
shored. Use care to insure that the duct installa- Htion is not disturbed by removal of shoring
materials.
e) Trench Bottom
1. The trench bottom should be smooth and free of any debris that may be detrimental to the
duct or impede the positioning of spacers.
2. Where the trench bottom is rocky, install a four-inch layer of compactable bedding material.
3. In direct burial appications, bedding must be uni-formly graded to provide continuous support.
4. Under no circumstances should blocking or mounding be used to raise the duct to grade.
5. Where an unstable trench bottom is encountered, it must be stabilized before laying duct.
Uually, this can be accomplished by over excavating and providing a bedding of crushed stone
or gravel to provide a stable base. This material should be suitably graded to act as an impervious mat through which the unstble soil will not penetrate.
f) Maximum particle size of the bedding material is typically 1 inch. A smaller maximum size may
be specified, to aid in placement around small-diameter duct and to prevent damage to the
duct wall.
f) Use care to prevent rocks, hard lumps, frozen clods, organic matter, and other foreign material from flling into the trench.
6.3 Trenchless Technology
6.3.1 Plowing and Planting.
