Utility Locators
Utility locators find and mark buried gas, electric, water, sewer and communication lines before anyone digs. The marks they make prevent strikes, fires and electrocutions. The job puts locators next to traffic, over unknown underground lines, and on every kind of terrain and weather.
- Construction
- Utilities
- Excavation
The color code
Most of the U.S. follows the American Public Works Association (APWA) uniform color code:
| Color | Meaning |
|---|---|
| Red | Electric power lines, cables, conduit and lighting cables |
| Yellow | Gas, oil, steam, petroleum or other flammable material |
| Orange | Communication, alarm or signal lines, cables or conduit |
| Blue | Potable water |
| Green | Sewers and drain lines |
| Purple | Reclaimed water, irrigation and slurry lines |
| Pink | Temporary survey markings |
| White | Proposed excavation |
See Call 811.
Working near traffic
- Wear Class 2 or 3 high-visibility apparel. See High-Visibility Clothing.
- Park so your truck shields you, use beacons and cones, and face traffic when you work if you can.
- Set up traffic control as your employer and the road authority require, especially on busy roads. See Work Zones.
- Watch for traffic before you step out of your vehicle and when you walk backward while marking.
Locating equipment
- Electromagnetic (EM) locators pick up signals from metal lines. Sometimes the locator puts a signal on the line (with a transmitter) at an access point.
- Ground-penetrating radar (GPR) can find non-metallic lines like plastic pipes and concrete duct banks. Results take training to read.
- No method is perfect. Soil, rebar, other lines and interference can give false readings. Use more than one method when you can, and compare with maps and records.
- Don’t connect a transmitter clamp or direct lead to a line that may be energized unless you’re trained and the procedure says it’s safe.
- Don’t probe or dig blind with a metal probe or bar into suspected gas or electric lines. Use soft digging or vacuum excavation to expose lines. See Hydro-Vacuum Excavation.
Marking
- Mark the path with paint, flags or stakes in the right color, and add the utility’s initials and width or size when you know it.
- Mark the whole job area as required by your state’s 811 law, including the tolerance zone distance.
- Don’t mark what you don’t know. Note uncertain results, and tell the excavator.
- Record what you found. See Private Utility Locating.
Other hazards
- Weather: heat, cold, lightning, wet ground and snow. Don’t use metal antennas or equipment in a thunderstorm. See Heat Illness.
- Manholes and vaults: open covers and confined spaces are not for locators to enter. See Confined Spaces.
- Overhead lines and equipment on the site
- Dogs, insects, uneven ground and unfamiliar yards
- Working alone: check in with your office. See Working Alone.
If you find a hazard or a strike happens
Mark the area and warn the crew. If someone hits a line, follow the 811 and utility emergency rules: stop work, keep everyone back, call 911 for gas or electric, and call the utility. See Utility Strikes.
Before each locate
- 811 ticket, maps and work area confirmed
- Locator tested and calibrated; batteries charged
- High-visibility apparel, vehicle beacons and cones ready
- Plan for traffic and for who knows where you are
- Paint, flags and stakes in the right colors
Standards & references
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