Staying safe near overhead power lines

Types of OHPLs

OHPLs, also called transmission or distribution lines, are supported by metal pylons or wooden poles and carry both high and low voltages. And both can kill.

The voltage of a line determines its height above ground. Lines carrying voltages up to 33kV must be at least 5.2m above the ground; pylons reaching voltages up to 400kV have a required minimum height of 6.7m – 7.3m. 

But whether high or low voltage, lines can be bare and uninsulated. If unsure about the status of a line and its level of insulation, assume it is uninsulated and consult the line’s owner or distribution network operator (DNO).

The legal requirements of working near OHPLs

Working near live OHPLs is only allowed by law when there is no alternative, and the risks have been assessed and are properly managed. Farmers must complete a site-specific risk assessment.

The OHPL owner - typically electricity companies, DNOs or organisations like Network Rail - are also responsible for minimising risks and advising on safety precautions when asked.

Reducing risk

While the safest approach is to avoid working near OHPLs altogether, this is not always possible. If work near OHPLs is unavoidable, there are some short and long-term safety options:

• If the OHPL is going to present a long-term or regular risk, contact the line’s owner or DNO to explore whether the line can be diverted or replaced with underground cables.
• In the short-term, or for tasks carried out less frequently, ask if the line can be switched off temporarily. Line owners/DNOs may charge for this service and require advance notice. If switching off is not an option, carry out a risk assessment to make sure the work can be carried out safely or do not proceed.

Conducting a risk assessment

Before working near OHPLs, assess the following:

• The type of work and whether access under or near the lines is required
• The height and voltage of the OHPLs – available from the line owner if unknown
• The maximum height and reach of machinery or equipment being used, including that used by contractors and external operators
• The safe clearance distance between lines and equipment – available from the line owner or Energy Networks Association
• The terrain and its potential effect on equipment stability.
• The training and supervision of workers on-site.

It is useful to record the location, voltage and height of OHPLs on a farm map, while also noting the required safe clearance distances. This can be used for planning future work or site access and updating contractors or new employees.

Practical safety measures

Reduce the risk of accidents near OHPLs further by doing the following:

• Establish safety zones by creating barriers extending at least 6m horizontally from the OHPL on all sides. These can include steel drums filled with rubble, concrete blocks, earthed wire fences or marked earth banks. Highlight barriers with red and white paint, flags or reflective strips to ensure they’re seen, especially at night.
• Install coloured flags or bunting 3-6m above ground level near an OHPL to alert operators of tall machinery.
• Do not stack materials or equipment within 10m of an OHPL where safety clearances could be compromised.
• Position rain/slurry guns so jet of fluid does not hit an OHPL, taking particular care in windy conditions, and check the jet breaker device is working.
• Where a power outage is pre-arranged or scheduled, confirm lines are not live before starting work.

Emergency procedures

If contact is made with an OHPL, follow these steps:

• Remain in the vehicle
• Warn others in the area to stay well clear
• Stay calm and call 105
• Use what3words to give the DNO your exact location so the power can be isolated
• Do not exit the vehicle until it’s been confirmed as safe to do so
• If it’s necessary to exit the vehicle sooner, for example if it catches fire, JUMP well clear. Do not touch the vehicle, it could be live!

For more detailed guidance, refer to “Avoiding danger from overhead power lines” available from hse.gov.uk.