Carrying out work near underground services
When underground cables are damaged, people can be killed and injured by electric shock, electrical arcs (causing an explosion), and flames. This often results in severe burns to hands, face and body, even if protective clothing is being worn.
Underground services are widespread. You must assume they are present unless you have been shown otherwise. There are many situations where underground services may be found and disturbed, including:
excavation, drilling and piling;
demolition and site remediation;
site investigation surveys;
any other work that involves penetrating the ground at or below surface level.
Damage can be caused when a cable is:
cut through by a sharp object such as the point of a tool; or
crushed by a heavy object or powerful machine.
If you are digging or disturbing the earth you should take care to avoid damaging underground services. Underground electrical cables can be particularly hazardous because they often look like pipes and it is impossible to tell if they are live just by looking at them.
Excavation work should be properly managed to control risks and it is easiest to break this down into four steps.
1. Planning the work
Most service cables belong to a Distribution Network Operator (DNO). However, some cables belong to other organisations such as the highways authority, Ministry of Defence or Network Rail.
You should check nearby for equipment owned by the organisations listed above, and if you suspect there are underground cables, ask them for plans to confirm their location. If underground cables are nearby you may need to ask someone from the organisation to come and accurately locate them for you.
If you are excavating near your own cables , then someone who is experienced in underground cable detection techniques should help you locate them using suitable equipment.
You may need to make underground cables dead for the work to proceed safely. Be aware that electricity companies are required to give five days' notice to customers whose supply is to be disconnected.
Careful planning and risk assessments are essential before the work starts. Risk assessments should consider how the work is to be carried out, ensuring local circumstances are taken into account.
2. Using cable plans
Plans or other suitable information about all buried services in the area should be obtained and reviewed before any excavation work starts.
If the excavation work is an emergency, and plans and other information cannot be found, the work should be carried out as though there are live buried services in the area.
Plans give only an indication of the location, and number of underground services at a particular site. It is essential that a competent person traces cables using suitable locating devices.
3. Cable locating devices
The position of the cable in or near the proposed work area should be pinpointed as accurately as possible by means of a locating device, using plans, and other information as a guide to the possible location of services and to help interpret the signal.
People who use a locator should have received thorough training in its use and limitations. Locating devices should always be used in accordance with the manufacturer's instructions, regularly checked and maintained in good working order.
4. Safe digging practices
Excavation work should be carried out carefully and follow recognised safe digging practices.
Once a locating device has been used to determine cable positions and routes, excavation may take place, with trial holes dug using suitable hand tools as necessary to confirm this.
Excavate alongside the service rather than directly above it. Final exposure of the service by horizontal digging is recommended, as the force applied to hand tools can be controlled more effectively.
Insulated tools should be used when hand digging near electric cables.