Underground services

Lesson Progress:
A cable avoidance tool and generator

Underground services include the following.

  • Electricity cables.
  • Sewers and drains.
  • Gas mains.
  • Telecommunications or fibre optics.
  • Water mains.
  • Oil or fuel pipes.

Thousands of service strikes happen every year. Many result in serious injury and some are fatal. It is vital that any excavation work, no matter how big, small, deep or shallow, is properly planned.

Before any excavation or digging, every effort should be made to locate existing services. These methods will show roughly where the services are.

  • Refer to service drawings.
  • Contact the utility company.
  • Carry out a ground radar survey.
  • Use cable avoidance tool detection (such as CAT and genny equipment).

Hand digging trial holes to expose the services is the most accurate way of locating them.

Examples of the services you are most likely to find and their relevant colours are shown below (this list is not exhaustive).

ServiceColour
Electricity (all voltages)Black or red
WaterBlue, black or grey
GasYellow
CommunicationsGrey, white, green, purple or black
The table above describes utility industry practice. However, not all apparatus will conform to the recommendations for colour coding. Some older utilities will have no marker tape or warning tiles.
Underground services

Safe systems of work may include the following.

  • Not using forks, picks or other bladed tools near live underground services.
  • Always treating services as live until confirmed otherwise.
  • Never assuming a service runs in a straight line.
  • Not using power tools or excavators within 500 mm of the indicated line of a service.

If you find an unexpected underground service, report it immediately.

If you strike a live service – if it is safe to do so, move away, do not go back, warn others and report it.