Underground Services Awareness

Underground services include gas, electricity, water, telecoms, sewers, and fibre optic cables buried below ground.
HSE Guidance Note HSG47 sets out the safe digging practices required before any ground penetration work.
Service strikes kill and seriously injure construction workers every year — electricity and gas are the highest risk.
Statutory undertakers' plans must be obtained and reviewed before any excavation or ground penetration begins.
Plans show approximate routes only — services can be up to 500mm from their indicated position on drawings.
A CAT (Cable Avoidance Tool) and Genny (Signal Generator) scan is required before any mechanical excavation.
Trial holes must be dug by hand to confirm the exact location, depth, and type of service before machine digging.
Services can be at any depth — do not assume a minimum cover, especially on previously developed land.
A valid permit to dig must be in place and briefed to the excavator operator and ground workers before starting.
Service colour coding in the UK follows a standard: blue for water, yellow for gas, black for electricity.

Prevent fatalities	Striking a live electricity cable or high-pressure gas main can kill the operator and nearby workers instantly.
Supply disruption	Damaging water mains, telecoms, or gas services causes major disruption to homes, businesses, and emergency services.
Legal prosecution	Failing to follow HSG47 safe digging procedures can result in HSE prosecution and significant fines for the contractor.
Repair costs	Service strike repairs including emergency response, reinstatement, and third-party claims cost tens of thousands per incident.

Do

Don't

Obtain and review statutory undertakers' plans before any ground penetration work begins.
Scan the area with a CAT and Genny before using any mechanical excavation equipment.
Dig trial holes by hand to expose and confirm the position of services shown on plans.
Obtain a valid permit to dig signed by the authorised person before starting excavation.
Brief the excavator operator on all known service locations and safe digging zones.
Mark service positions on the ground using spray paint, markers, or flags after locating.
Hand dig within 500mm of any confirmed or suspected underground service position.
Report any service found that is not shown on the plans to the site manager immediately.
Stop work and follow the emergency procedure if a service is struck or damaged.
Ensure the CAT operator holds a valid training certificate and is competent in its use.

DON'T excavate without first reviewing service plans and completing a CAT scan of the area.
DON'T assume plans are accurate — services can be offset from the position shown on records.
DON'T use a mechanical excavator within 500mm of a known or suspected service.
DON'T use pointed hand tools such as pickaxes or forks near buried services.
DON'T continue digging if you see warning tape, marker tiles, or unexpected ducting.
DON'T rely on a CAT scan alone — always verify with trial holes dug by hand.
DON'T start digging without a valid, signed, and briefed permit to dig in place.
DON'T touch or attempt to repair a damaged gas or electricity service yourself.
DON'T assume services will always be at standard depth — they may be shallow or diverted.
DON'T allow untrained operatives to use CAT and Genny detection equipment on site.

See also: Cat and Genny Safe Use | Service Strike Emergency Procedure

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