On average two people are killed and many more are injured every year as a result of coming into contact with overhead power lines (OHPLs) during agricultural work. Contact with OHPLs rarely results in minor injuries. Machinery (such as combines and tipping trailers), equipment (such as irrigation pipes and ladders) and activities such as bale stacking are often involved.
As part of the Health & Safety Executive’s ongoing programme of farm inspections, safety around overhead power lines is an area that inspectors have been focusing on. During these inspections, inspectors are asking our clients about the location and types of OHPLs on their farms, how they work safely in the vicinity of OHPLs and what actions should be taken if you come into contact with one.
Below is a guide to the information a HSE inspector might ask a farmer during an inspection, to demonstrate that they are aware of the risk.
Types of overhead power lines and their heights
Most OHPLs have wires supported on metal towers/pylons or wooden poles – they are often called ‘transmission lines’ or ‘distribution lines.’ Some examples are shown at the end of the piece.
Most high-voltage OHPLs, i.e., greater than 1000 V (1000 V = 1 kV) have wires that are bare and uninsulated, but some have wires with a light plastic covering or coating. All high-voltage lines should be treated as though they are uninsulated. While many low-voltage overhead lines (i.e., less than 1 kV) have bare uninsulated wires, some have wires covered with insulating material. However, this insulation can sometimes be in poor condition, or, with some older lines, it may not be effective. In these cases, you should treat the line in the same way as an uninsulated line. If in any doubt, you should take a precautionary approach and consult the owner of the line.
What does the law require?
The law states that work may be carried out in close proximity to live OHPLs only when there is no alternative and only when the risks are acceptable and can be properly controlled. You should use this guidance to prepare a risk assessment that is specific to the site. Guidance on how to carry out a risk assessment is available at Managing risks and risk assessment at work – Overview -HSE
Businesses and employees who work near to an OHPL must manage the risks. OHPL owners have a duty to minimise the risks from their lines and, when consulted, advise others on how to control the risks. The line owner will usually be an electricity company, known as a transmission or Distribution Network Operator (DNO), but could also be another type of organisation, e.g., Network Rail, or a local owner, e.g., the operator of a caravan park.
Remove the risk
The most effective way to prevent contact with OHPLs is by not carrying out work where there is a risk of contact with, or close approach to, the wires.
If you cannot avoid working near an OHPL and there is a risk of contact or close approach to the wires, you should consult its owner to find out if the line can be permanently diverted away from the work area or replaced with underground cables. This will often be inappropriate for infrequent, short-duration or transitory work.
If this cannot be done and there remains a risk of contact or close approach to the wires, find out if the OHPL can be temporarily switched off while the work is being done. The owner of the line will need time to consider and act upon these types of requests and may levy a charge for any work done.
If the OHPL cannot be diverted or switched off, and there is no alternative to carrying out the work near it, you will need to think about how the work can be done safely. If it cannot be done safely, it should not be done at all. Your site-specific risk assessment will inform the decision.
Points to consider as part of your risk assessment include:
- The voltage and height above ground of the wires. Their height should be measured by a suitably trained person using non-contact measuring devices.
- The nature of the work and whether it will be carried out close to, or underneath the overhead line, including whether access is needed underneath the wires.
- The size and reach of any machinery or equipment to be used near the OHPL.
- The safe clearance distance needed between the wires and the machinery or equipment, and any structures being erected. If in any doubt, the OHPLs owner will be able to advise you on safe clearance distances.
- The site conditions, e.g., undulating terrain may affect stability of plant etc.
- The competence, supervision and training of people working at the site.
- If the OHPL can only be switched off for short periods, schedule the passage of tall plant and, as far as is possible, other work around the OHPL for those times. Do not store or stack items so close to OHPLs that the safety clearances can be infringed by people standing on them.
- Where there will be no work or passage of machinery or equipment under the OHPL, you can reduce the risk of accidental contact by erecting ground-level barriers to establish a safety zone to keep people and machinery away from the wires. This area should not be used to store materials or machinery. Suitable barriers can be constructed out of large steel drums filled with rubble, concrete blocks, wire fence earthed at both ends, or earth banks marked with posts.
- If steel drums are used, highlight them by painting them with, for example, red and white horizontal stripes.
- If a wire fence is used, put red and white flags on the fence wire.
- Make sure the barriers can be seen at night, perhaps by using white or fluorescent paint or attaching reflective strips.
The safety zone should extend 6 meters horizontally from the nearest wire on either side of the overhead line. You may need to increase this width on the advice of the OHPL owner or to allow for the possibility of moving parts encroaching into the safety zone. It may be possible to reduce the width of the safety zone, but you will need to make sure that there is no possibility of encroachment into the safe clearance distances in your risk assessment.
Where plant such as a crane is operating in the area, additional high-level indication should be erected to warn the operators. A line of coloured plastic flags or ‘bunting’ mounted 3–6 m above ground level over the barriers is suitable. Take care when erecting bunting and flags to avoid contact or approach near the wires.
Emergency procedures
If someone or something comes into contact with an OHPL, it is important that everyone involved knows what action to take to reduce the risk of anyone sustaining an electric shock or burn injuries.
Key points are:
- Never touch OHPL wires
- Always assume that the wires are live, even if they are not arcing or sparking, or if they otherwise appear to be dead.
- Remember that, even if OHPLs are dead, they may be switched back on either automatically after a few seconds, or remotely after a few minutes or even hours if the line’s owner is not aware that their line has been damaged.
- If you can, call the emergency services. 105 is the DNO National emergency number. Give them your location (What3Words reference would be useful to pinpoint the exact location). Tell them what has happened and ask them to contact the OHPL owner.
- If you are in contact with, or close to, a damaged wire, move away as quickly as possible and stay away until the OHPL owner advises that the situation has been made safe.
- If you are in a vehicle that has touched a wire, either stay in the vehicle or, if you need to get out, jump out of it as far as you can. Do not touch the vehicle while standing on the ground. Do not return to the vehicle until it has been confirmed that it is safe to do so.
- Be aware that if a live wire is touching the ground the area around it may be live. Keep a safe distance away from the wire or anything else it may be touching and keep others away.
Read further guidance from the Health & Safety Executive (HSE) on avoiding danger from overhead power lines: Avoiding danger from overhead power lines GS6 (hse.gov.uk)
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| 275 kV transmission line | 11 kV distribution line | 400 V distribution line |
