Underground services safe digging
Plan buried service searches, permits, cable avoidance scans, trial holes, and emergency actions before excavation starts.
What counts as a buried service?
Buried services are underground utility assets such as electricity cables, gas pipes, water mains, sewers, telecoms ducts, street lighting cables, fuel lines, and private site services. HSG47, the HSE guidance on avoiding danger from underground services, expects a safe system based on plans, locating, marking, safe excavation, and emergency arrangements.
CAT
Cable avoidance tool. It detects some buried metallic services and live power signals, but it cannot prove an area is service-free.
Genny
Signal generator used with a CAT to apply a traceable signal to a service or tracer wire.
Permit
A permit to dig is the site control that confirms plans, scans, markings, method, supervision, and emergency contacts before breaking ground.
Check the digging risk
Set the current controls. The result highlights the controls that need attention before excavation starts.
Digging status
Proceed only under the permit
Core controls are in place. Keep the permit live and stop if the ground does not match the information.
Open controls
Control cards
The selector highlights the controls most likely to need action. A clear CAT scan does not remove the need for plans, markings, and cautious excavation.
Utility plans and site walkover
Gather records from utility owners, the client, previous contractors, and site operators. Compare drawings with covers, cabinets, lighting columns, meters, poles, scars, chambers, and service entries.
Treat records as aids, not proof. Private services and abandoned assets are often missing.
CAT and Genny survey
Use the correct modes and mark routes clearly on the ground. The person using the equipment must understand its limits and the type of services expected.
Non-metallic pipes, unenergised cables, deep services, and congested corridors can be missed.
Permit to dig
The permit should confirm the scope, drawings used, scan record, marked routes, method, authorised plant, hand-dig zones, supervision, and emergency contacts.
Reissue or amend the permit if the dig line, depth, plant, or ground conditions change.
Trial holes and exposing services
Use hand digging or vacuum excavation to prove line and level where the route affects the work. Support exposed services and protect them from plant, materials, and traffic.
Do not assume a service follows a straight line between visible points.
Mechanical excavation controls
Use machines only where controls show it is safe to do so. Keep bucket teeth, breakers, augers, and trenching attachments away from marked or suspected routes until services are exposed.
Use a banksman where visibility, public interface, or service congestion creates extra risk.
Emergency response
Brief workers on what to do if a cable, pipe, duct, or unknown object is struck or exposed. Keep utility emergency numbers and site location details available at the work face.
Stop work, keep people away, and contact the asset owner or emergency services where needed.
Permit checklist
Use this before breaking ground. If any item is uncertain, stop and improve the information before the excavation starts.
Emergency actions after a strike
These are prompts for briefing and emergency planning. Follow the asset owner's emergency instructions and call emergency services where there is immediate danger.
Electric cable
Stop work, keep people away, avoid touching plant or exposed conductors, and contact the network operator. If plant is live, the operator should stay in the cab if safe to do so until told otherwise.
Gas or fuel pipe
Stop work, extinguish ignition sources, evacuate upwind where possible, prevent vehicles entering the area, and call the gas emergency number or emergency services.
Water, sewer, or telecoms
Stop work, protect the area, prevent collapse or flooding risks, and contact the asset owner. Do not backfill or conceal damage before it is assessed.
Sources
- HSE HSG47 avoiding danger from underground services - core guidance for plans, locating, safe digging, and emergency controls
- HSE buried services safety topic - construction guidance for underground services
- HSE excavation near underground electrical cables - electrical service strike guidance
- PAS 128 underground utility detection specification - BSI publicly available specification for detection, verification, and location
- CDM 2015 Regulation 25 - energy distribution installation precautions
- HSE CIS80 construction phase plan - construction phase planning prompts under CDM 2015
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