Last Updated: November 1, 2026
Quick Summary
Underground cable safety for groundworkers comes down to planning before digging, locating services with a CAT and Genny scan, confirming with trial holes, and digging by hand near known cables. Out-of-date records and skipped checks cause most strikes. A clean scan is never a guarantee the ground is clear.
Every year, groundworkers strike buried cables that nobody expected to find. Most of these strikes are not caused by bad luck. They happen because plans are out of date, locators are misread, or the dig starts before anyone checks what is underneath.
The reasons are usually simple. Service records are incomplete. Old cables were never recorded. Temporary supplies appear mid-project. Under pressure to hit a programme date, crews skip checks they would never skip on a quiet day. Each of these is a problem that good habits can fix.
The ten tips below set out how to plan, locate, dig and respond. Each one is practical, and each one is something a site team can start on Monday.
Planning is where most cable strikes are prevented, and it is the cheapest place to fix them.
Tip 1: Request service records early. Contact the utility owners and ask for plans of their apparatus in the work area. Do this well before the programme requires it, because records can take time to arrive.
Tip 2: Walk the site with the plans. Check the drawings against what you can see on the ground: manhole covers, marker posts, street furniture and old ducts.
Tip 3: Write a dig plan for each area. Record the route, expected depth, the services present and the controls in place.
A dig plan only works if the people digging have read it. Brief the gang, not just the site manager.
Records tell you where cables should be. A locator tells you where they actually are.
Tip 4: Use a CAT and Genny scan on every dig, and know which mode you are in. A Cable Avoidance Tool (CAT) with a Genny signal generator is a common way to trace live cables.
Tip 5: Mark what you find, and mark it precisely. Use paint or flags to mark each service on the ground as you locate it.
Tip 6: Confirm with trial holes before machine work. Where a service is close to the planned excavation, use hand digging or vacuum excavation to expose it before using a machine.
A locator can miss cables that are not live, cables that are deeper than expected, and cables that are not in the signal path at all. Ground conditions, nearby metal, reinforced concrete and poor connections can distort readings. Two failure modes are worth knowing about specifically. First, a signal can “bleed” onto adjacent services, so the peak reading may sit on a pipe rather than the cable you are looking for. Second, a cable that is not connected to anything at the time of the survey may carry no passive signal and may not accept an active signal, so it can be invisible to the tool.
The three locating steps in this section each rely on a clear action, so the key points are easy to scan.
| Tip | What to do | Key point |
|---|---|---|
| Tip 4 | Scan the full dig width with CAT and Genny | Know whether you are in passive or active mode |
| Tip 5 | Mark each located service on the ground | Mark the line, not just the peak point |
| Tip 6 | Confirm with trial holes before machine work | Trial holes show true depth and condition |
Even with a good plan and a clean scan, the digging itself needs care.
Tip 7: Dig by hand near known services. Within a safe distance of a located cable, switch to hand digging or suction tools. Machines should stop well short of the marked line.
Tip 8: Protect cables and keep warning tape visible. Where cables are exposed or near the surface, use protection such as tiles, ducts or ramps. Check that warning tape is in place above buried services and remains visible during backfilling. Tape and mesh give warning to the next person who digs, and they also reduce the risk of a strike if the cable is reached.
Safe digging depends on what people do every day, not on one good plan. Short, regular briefings keep cable safety in front of the team.
Many groundworkers know the rules but struggle to act on them under pressure. Regular practice and clear expectations from supervisors close that gap.
Most guides stop at prevention. The first hour after a strike is where outcomes are decided, and it is the part groundworkers are least prepared for. If a cable is struck, the first priority is to keep everyone safe. Stop work, move people away from the area, and do not touch the damaged cable or any exposed conductor. Assume it is live, even a cable that was thought to be dead can be re-energised, and a damaged cable can arc without anyone touching it.
A cable strike is a reportable event in most cases. Under the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations (RIDDOR), certain dangerous occurrences, including electrical incidents that cause injury or fire, must be reported to the Health and Safety Executive. The site’s health and safety lead should confirm whether the strike meets the reporting threshold and make the report within the required timescale. Separately, the network operator will want its own incident report, and the site should keep a record that includes the time, location, services involved, the locating method used, the dig plan, and witness statements.
A short, factual incident report is worth more than a long one written a week later. Capture it the same day, while memories and marks are fresh.
Once the area is safe and the reports are filed, review what happened against the dig plan and the locating record. Common findings include plans that were out of date, a scan that was not repeated after the dig moved, marks that were lost during backfilling, or a machine that was used closer to the service than the plan allowed. Feed those findings into the next briefing so the whole gang learns from the event, not just the people who were there.
Use this before work starts in any new area:
Keeping this checklist on the site notice board or in the daily briefing pack makes it hard to skip a step.
Good plans and good locating only work when the people on site understand the risks and act on them. SJB Electrical Training delivers specialist, hands-on electrical safety and compliance training across the UK, including HSG47 and GS6 training, for contractors, maintenance teams and industrial organisations. Check our upcoming course dates to find a session that suits your team, or browse our electrical training courses to see what is available. If you want to compare options first, our HSG47 and GS6 excavation compliance guide sets out what the standards require. Book Training today to make sure your groundworkers know what to do when they are near a live cable.
Before any excavation starts, obtain plans of buried services, confirm the position of cables on site, and agree a method of working with the team. Use a cable avoidance tool to trace live cables, expose them by hand or with a suitable soft-dig method where they run close to the planned excavation, and keep mechanical plant clear of the marked route. Warning tape and marker mesh help signal cables to later workers. Anyone working close to cables should wear suitable protective equipment and be briefed on what to do if a strike occurs.
HSG47, the HSE guidance on avoiding danger from underground services, recommends that duty holders gather information about buried services before work starts, including records from utility owners and the site survey. The guidance then expects a risk assessment, a plan for locating and identifying services, and suitable precautions for the chosen method of excavation. Briefing everyone involved and keeping the plan under review as the dig progresses are both part of the process.
No. A cable locator, such as a CAT and Genny combination, can trace cables and pipes, but signals can be distorted by nearby services, and some cables cannot be detected reliably at all. Locators support a planned approach rather than replacing it. Use the tool to confirm what the records show, mark the route clearly, and expose the cable by hand or with a suitable soft-dig method before using mechanical plant nearby.
Stop work immediately, keep people clear of the area, and do not touch the damaged cable or attempt a repair. Treat every cable as live until its owner confirms otherwise. Call the emergency number for the network operator, follow the site emergency procedure, and report the incident to your supervisor. Record what happened so the strike can be reviewed and the method of working improved.
