Electrical Estimating Methods, 4th Edition

CHAPTER 19 Electrical Utilities

Electric utilities include the site work required for the installation of electrical power or telephone/data wires and the actual underground installation of those wires or cables. This chapter addresses electrical and communication site work and underground duct bank. Each of these components is described in terms of what is included and required—for both materials and labor. A takeoff procedure is also provided.

ELECTRIC SITE WORK

This category covers the distribution methods used to route power, control, and communications cables onto a facility's property and between its buildings and structures. There are three basic options: direct burial cables, underground in duct banks, and overhead on poles.

Direct burial cables are the least versatile; they are generally used for residential applications where aesthetics are a more important factor than flexibility or an allowance for future changes. Occasionally, direct burial is used in commercial and industrial facilities to route a branch feeder to unique equipment, such as a well pump or roadway lighting. Two techniques are used to place direct buried cables. A trenching machine may dig a narrow slot two to four feet deep for a single cable or a trench one to two feet wide for multiple cables. The trench is usually backfilled with a few inches of sand—below and again above the cables—for protection. About 12 inches above the cable, concrete planks or plastic marker tape may be placed as a warning ...