The Definition of Underground Utility Locate
Underground utility locate is the process of identifying and marking buried utilities before excavation to prevent strikes.
Underground utility locate is the process of identifying and marking buried utilities before excavation to prevent strikes.

The process of identifying and marking the location of buried utility lines — such as gas, electrical, water, and telecommunications — before excavation begins, typically using utility maps, locating equipment, and standardized color-coded markings to prevent accidental strikes.
Before digging for a new fence line, a contractor submits a locate request through a one-call notification center, and utility companies mark the area with colored flags and paint indicating buried gas and electrical lines.
Most jurisdictions require locate requests, often through a national "call before you dig" service, to be submitted a minimum number of business days before excavation, commonly two to three days.
Standardized colors are used to identify utility types — for example, red typically indicates electrical lines, yellow indicates gas or oil, and blue indicates potable water, though standards can vary by region.
Work should stop immediately, the area should be evacuated if gas or electrical hazards are suspected, and the utility company and emergency services should be notified right away.