CAT and Genny Safe Use

A CAT (Cable Avoidance Tool) detects electromagnetic signals from buried cables and metallic pipes.
A Genny (Signal Generator) applies a signal to a specific service so the CAT can trace its route precisely.
HSE guidance HSG47 requires a CAT and Genny scan before any excavation or ground disturbance work.
Service strikes injure hundreds of workers each year through electrocution, burns, and gas explosions.
A CAT scan alone is not sufficient — service plans must also be obtained and reviewed before digging.
The CAT has four modes: Power, Radio, and Genny — all three must be used for a thorough scan.
Operators must hold a valid competency card and be trained in the specific model of CAT being used.
The CAT will not detect all services — plastic gas pipes and fibre optic cables produce no signal.
A pre-use check must be carried out on the CAT and Genny before every shift to confirm they are working.
Trial holes using hand digging should be used to confirm the exact location and depth of detected services.

Prevent electrocution	Striking a live electrical cable can kill instantly — a CAT and Genny scan locates cables before you dig.
Prevent gas explosion	Puncturing a gas main during excavation can cause an explosion that injures or kills workers and the public nearby.
Legal duty	HSG47 requires service detection before all excavation work; failure to scan is a breach of your duty of care.

Do

Don't

Obtain and review up-to-date service plans before scanning or digging any area.
Carry out a pre-use check on the CAT and Genny at the start of every shift.
Scan in all three modes — Power, Radio, and Genny — for a thorough survey.
Walk the entire dig area in a grid pattern, scanning in two directions at right angles.
Use the Genny to apply a signal and trace specific services along their exact route.
Mark detected services clearly on the ground using spray paint or marker posts.
Dig trial holes by hand to confirm the position and depth of detected services.
Ensure your CAT and Genny training and competency card are current and valid.
Hand dig within 500mm either side of any detected service location.
Report any uncharted or unexpected services found during excavation immediately.

DON'T dig without first reviewing service plans and completing a CAT and Genny scan.
DON'T use a CAT or Genny without carrying out a pre-use function check.
DON'T rely on Power mode alone — use all three modes for a complete scan.
DON'T scan in only one direction — always sweep in two perpendicular directions.
DON'T assume a clear scan means there are no services — some are undetectable.
DON'T excavate over unmarked service routes without confirming their position first.
DON'T use a machine excavator within 500mm of a known service location.
DON'T operate a CAT or Genny without valid training and a competency card.
DON'T ignore depth estimates — services may be shallower than records indicate.
DON'T continue digging if you find an unexpected pipe, cable, or duct.

See also: Service Plan Reading & Interpretation | Safe Digging Practices (HSG47)

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