Dry utilities is the installation of the electric, telephone, TV, internet, and gas in a community.

In this post we will be discussing:

1. Joint Trench
2. Mainline vs. Crossings
3. Joint Trench Detail
4. Dry Utility Structures

JOINT TRENCH

The subcontractor will generally install just the conduit for these utilities, and then the utility companies will then pull their own cable through after. And since the conduit for all these utilities typically go in the same trench as one another*, we call this the “Joint Trench”.

Unlike the wet utilities, the conduit for the drys is generally installed next to the road BEHIND the curb & gutter, NOT in the street.*

*PLEASE NOTE: The conduit/trench layout and construction requirements may be different in other areas and states. It all depends on the standards laid out by your local utility companies and governing jurisdictions.

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MAINLINE VS. CROSSINGS

The “mainline” is the joint trench installation behind the curb (as previously discussed). The “crossings” refer to the conduit that crosses the street. Knowing the difference between the crossings and the mainline is significant because the sub will typically install these at different times. The reason being sometimes the electrical plans aren’t finalized, but the crossings still need to go in BEFORE the streets are paved! Then usually the subcontractor will return later to install the mainline.

JOINT TRENCH DETAIL

A typical joint trench is about 24″ wide and a minimum of 54″ deep (see below for detail). And keep in mind, depending on the design and the schematics of your job you could have multiple runs of electric conduit within the same trench (sometimes even up to five!).

In between each set of utilities is a layer of sand we call “sand shade” or “sand bedding“.

Sand is important because it provides a good buffer for each set of utilities. It does not expand or contract very easily, thus making the pipe less susceptible to damage. It also stays cool, thereby reducing the amount of heat transferred to the utilities. The sand also serves as a warning when others are digging near these utilities because of its gray color.

DRY UTILITIES STRUCTURES

The dry utilities system also consists of the installation of structures in addition to the conduit. Structures consist of “handholes” and “pull boxes” (as well as transformers, PME boxes, and much more for the electrical system, which we’ll talk about in a later post). You’ve probably seen these installed in the ground out in your front yard.

The handholes house the electrical system and allow future access for any further construction or maintenance. The pull boxes are the locations through which the wire can be pulled through the conduit.

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**Be sure to watch the video below to view some actual Dry Utility plans!

<< Wet Utilities Introduction (Post #3)

Street Improvements Introduction (Post #5) >>