This HSE information sheet is for employers of people who work on agricultural machinery or equipment.

If machinery comes into contact with a live overhead electricity power line, anyone touching it risks a serious or fatal electric shock. The guidance gives advice on reducing the risks of electric shock.

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Introduction

This information sheet is aimed at everyone in agriculture who may work near overhead electricity power lines (OHPLs) and outlines what you can do to reduce the risks of electric shock when working near them. If a machine or other conductive item of equipment comes into contact with a live OHPL, electricity will be conducted through it to earth. You do not need to touch the line, as in some circumstances electricity can flashover or arc (it can jump across gaps). Anyone touching a machine or equipment in these circumstances risks a serious or fatal electric shock.

Hazards

OHPLs typically carry electricity at voltages from 11 kV to 400 kV. The lines are often uninsulated (bare) cables. Touching anything in contact with live electrical equipment (even at the lowest voltage) can be fatal. The height of the line varies according to the voltage carried (see Figure 1) so for example any 11 kV or 33 kV OHPL on your land should be at least 5.2 m above the ground.

Electrical equipment mounted on poles may be lower than the clearances specified in this guidance. Although the minimum heights of OHPLs may be adequate for most work activities, there are many agricultural machines that are capable of reaching or touching OHPLs or pole-mounted equipment, including:

■ rough terrain fork lift trucks and telescopic materials handlers;
■ combine harvesters;
■ self-propelled harvesters, eg forage harvesters, beet harvesters etc;
■ crop sprayers; n tractors and tractor-mounted fore end loaders.

Remember that the overall height of a machine may be increased by fitting radio aerials, flashing beacons or in the case of combine harvesters, when the discharge auger or grain tank extensions are used. Other machines often used in agriculture are capable of reaching an OHPL, including:

■ construction plant, such as excavators or diggers;
■ goods vehicles with tipping bodies or trailers; n lorry-mounted or self-propelled cranes or grabs.

Some agricultural activities may also create a risk of contacting OHPLs, including:
■ operating rain or slurry guns;
■ tipping trailers;
■ moving irrigation pipes or long boom irrigators;
■ building temporary stacks or structures, eg bales, fertiliser, potato boxes;
■ moving aluminium ladders or scaffold poles;
■ construction work including erecting steel-framed buildings;
■ erecting polytunnels and temporary structures;
■ fishing (electricity can pass through rods/poles).

Working safely: Assessing the risks

Before you start work near OHPLs, you should assess the risks. To help do this you should:
■ find out the maximum height and maximum vertical reach of your own and your contractors’ machines;
■ find out the routes of all OHPLs on your land or near your boundaries and mark them on the farm map;
■ make sure you have information about all the lines on your land – if not, contact their owners;
■ make sure you have details of the maximum working heights permitted under each span of OHPL on your farm and next to each structure. Record these on the farm map. The map can then be used as a reference when assessing risks, planning cropping or other work, instructing machine operators and contractors, planning access routes or buying new or used equipment;
■ get advice from the electricity distribution network operator (DNO) and/or the National Grid on line heights, minimum vertical clearance distances and precautions to take. DNOs can also arrange to have the height of the lines checked. Operating voltages are displayed on signs attached to steel towers;
■ look at the guidance produced by the Energy Networks Association on clearance distances (see ‘Further reading’).

Control measures

When considering what you need to do to work safely, you should follow the preferred hierarchy of measures described below:

■ The safest option is always to avoid working near OHPLs if you can. Creating alternative access routes or work areas to avoid OHPLs is often the easiest and cheapest option.
■ Consider re-routing or burying OHPLs in certain locations, such as farmyards or silage clamps where machines often pass below the lines. Consult the DNO for advice and do not attempt to do this work yourself.
■ Where you cannot relocate OHPLs, select machines that can safely pass below the lines without being able to reach the vertical clearance distance.
■ For some short duration work activities you may be able to get the power supply switched off. Speak to the DNO for advice.
■ Where you cannot avoid working near OHPLs, you will need to carry out a risk assessment and implement a safe system of work.

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