Toolbox Talk – Power Lines & You

Today’s Toolbox Talk focuses on Power Lines & you, taking a look at some of the safety aspects when working closely to power lines. An overhead power line is a structure used in electrical power transmission and distribution to transmit electrical energy across large distances. The line consists of two main parts, namely pylons known as the tower and conductors which are the wires. No structure may be erected above or below the surface of the ground within a specified distance (depending on the voltage) of the centre line of any power line or within 10m of any tower.

Voltages less than 230v can kill and overhead powerlines (OHPL) run between 400v and 400kv. This means the higher the voltage that is transmitted through the power lines the more dangerous. The higher voltage cables are not insulated but gloves and rubber boots are not adequate protection for voltages in OHPL. It is not necessary to touch the OHPL to receive a shock – regardless, close proximity can produce a fatal arc.

Employers and workers have a duty to ensure:

• Risks are assessed by a competent and experienced person.
• Safety precautions are always followed.
• Overhead line wires should never be touched.
• It is always assumed that the wires are live. Even if thought to be isolated or dead, they may be switched back on either automatically or remotely after a few seconds, minutes or even hours.
• If working in proximity to broken lines, they are to be isolated and earthed at a safe distance either side of the working area.

Step potential: 

When voltage is higher nearer the source – as you step away one foot may be in contact with a lower voltage than the other. Current will flow through your body, as you lift one foot, and arc back to earth giving a shock likely to be fatal.

Touch potential: 

When you touch a live source, and the voltage is higher than your feet. Current will flow through you to the floor delivering a shock that could be fatal due to high voltage.

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