Last Updated: September 17, 2026
HSG47 and GS6 compliance is the practice of controlling the risks from underground services and overhead power lines during excavation work, following two separate Health and Safety Executive publications: HSG47 for buried services and GS6 for overhead lines. At SJB Electrical Training, we see the same pattern on site visits: crews can recite the regulations but freeze when the cable locator sounds off near a live service.
An HSG47 excavation safety checklist works only if it is followed in order: plan, locate, mark, dig with care. Skipping the planning stage is the most common failure we see, and it is the one that turns a routine trench into a cable strike.
Planning starts with service plans from every utility provider in the area, requested well before the dig date. These plans show approximate routes only, so they inform the survey rather than replace it. A permit to work should be raised for any excavation near services, and the safe system of work must name the competent person responsible for the locator survey.
Locating means sweeping the ground with a cable avoidance tool and signal generator, then marking every detected service with paint or pegs. A common mistake is treating a single sweep as final. Locators have known limitations, and the guidance is to use them alongside service plans, not instead of them.
A GS6 risk assessment template should capture four things for every overhead line: its voltage level, its height, the plant that will pass beneath it, and the exclusion zone you will enforce. Generic templates fail because they treat all overhead lines the same.
Structure your assessment around these fields:
Safe clearance distances for overhead power lines depend on voltage, and getting them wrong is an electrocution risk, not a paperwork problem. The guidance sets minimum distances that increase with voltage, and these apply to people, plant, and anything that could be lifted or extended.
| Voltage Level | Typical Minimum Clearance | Key Control |
|---|---|---|
| Low voltage (up to 1kV) | 1 metre | Warning signs, tool box talk |
| 11kV to 33kV | 3 metres | Goalposts, exclusion zone |
| 132kV | 6 metres | Permit to work, banksman |
| 275kV to 400kV | 7 metres or more | Network operator involvement |
A clearance figure on its own is useless until it is converted into a physical control on the ground. Work through this sequence every time:
Goalposts are the standard control where plant must pass beneath a line. They are two vertical posts with a horizontal member set at the safe clearance height, positioned so that any machine that would breach the distance physically cannot pass. The HSE guidance on avoiding danger from overhead power lines sets out the goalpost and barrier expectations in detail.
What most guides miss is that the clearance assessment must be revisited if the plant changes mid-project. A new crane with a longer jib, a larger excavator brought in for a deeper dig, or a delivery vehicle with a taller load all invalidate yesterday’s assessment. The safe system of work should name who is responsible for re-assessing when plant changes, and the permit to work should be re-raised rather than amended in the margin.
Electrical safety training for contractors only sticks when it changes behaviour on the ground, not just test scores. Subcontractors are the hardest group to manage because they arrive with varying competence levels and their own habits.
Most guides tell you to check training certificates at the gate. That is too late. A subcontractor who cannot evidence HSG47 and GS6 competence should not be on the programme in the first place. Build the check into procurement, not induction.
Ask for these before the contract is awarded:
What works, in our experience:
The highest-risk moment on a shared site is the handover between trades. A groundworker marks a service, then a different subcontractor’s machine operator arrives the next day and does not know the marks are there. The permit to work should name every trade working in the excavation, and the competent person should brief each incoming crew on the marks and the exclusion zones before they start.
Digital mapping tools have changed how sites plan around utility infrastructure, but they have not replaced the physical locator survey. The two work together: digital plans narrow the search area, and the locator confirms what is actually buried.
Emergency procedures must be displayed, rehearsed, and specific to the site. If a cable is struck, the immediate actions are: stop work, keep everyone back, do not touch anything, and call the network operator’s emergency line. Attempting to move a damaged cable or a machine in contact with one is how electrocution happens.
The hardest part of HSG47 and GS6 compliance is not learning the rules; it is making them survive contact with a busy site and a tight programme. Compliance that lives in a folder does nothing for the groundworker standing next to an unmarked service.
HSG47 covers avoiding danger from underground services, focusing on planning, locating cables with service plans and cable avoidance tools, and safe digging practices. GS6 deals with avoiding danger from overhead power lines, setting out exclusion zones and safe clearance distances based on voltage levels. Together they form the core of excavation safety and electrical hazards management on site, and a combined HSG47 and GS6 compliance guide should treat them as one operational system rather than two separate documents.
The duty holder, typically the principal contractor or site manager, carries overall responsibility under CDM 2015 and the Electricity at Work Regulations 1989. That duty of care extends to everyone on site, including subcontractors. In practice this means providing service plans, enforcing permit to work systems, delivering site inductions and toolbox talks, and appointing a competent person to oversee hazard identification and safe systems of work.
Follow a clear sequence: obtain and review utility service plans, scan with cable avoidance tools, mark the ground, use safe digging practices such as hand tools near services, and maintain safe working distances. Never assume a service plan is accurate. Treat every cable as live until proven otherwise, and stop work immediately if you strike or expose anything unexpected, then follow your emergency contact and incident reporting protocols.
Identify the voltage levels of overhead power lines from the utility infrastructure operator, then establish exclusion zones with barriers and goalposts that keep plant and people at the correct safe working distance for that voltage. Where plant cannot maintain clearance, use permit to work controls, banksmen and, where required, isolation. Site induction and toolbox talks should reinforce these limits daily, especially for tipper lorries, excavators and scaffold towers.
Anyone supervising or undertaking excavation near services, or working near overhead power lines, needs a level of competence matched to their role. That usually means a recognised HSG47 and GS6 course, plus a valid cable avoidance tool qualification. Electrical safety training for contractors should also cover emergency procedures, permit to work systems and how to read service plans. Refresher training keeps knowledge current when regulations, equipment or site conditions change.
Failing to follow HSE guidance such as HSG47 and GS6 can breach the Health and Safety at Work etc. Act 1974, the Electricity at Work Regulations 1989 and CDM 2015. Consequences include prohibition notices, unlimited fines, prosecution of duty holders and, in the worst cases, custodial sentences. Beyond enforcement, a cable strike or overhead line contact can cause electrocution, burns and site shutdowns, so compliance is both a legal and a commercial necessity.
