Nobody working in the construction industry here in the UK could fail to be aware of the dangers involved when working near overhead power lines. Regulation 14 of the Electricity at Work Regulations 1989 states that work may be carried out in close proximity to live overhead lines only when there is no alternative and when the risks can be properly controlled. Any distance within 10 metres (measured horizontally at ground level from below the nearest cable) is classed as close proximity.
A voltage of 230v or less can kill and overhead powerlines run between 400v and 400kv. The higher voltage cables are not insulated and gloves and rubber boots do not provide protection for the voltages in overhead powerlines (OHPL). You don’t even need to be touching the powerline to get a shock, just being in close proximity can create a fatal arc.
Although the line should be isolated or temporarily diverted, this is not always possible so employers need to ensure that they take suitable precautions to protect employees. Employers and workers have a duty to ensure that:
·Risks are assessed by a competent and experienced person
·Safety precautions are always followed
·Overhead line wires should never be touched
·Always assume that the wires are live, even if they are thought to be isolated they may be switched on automatically or remotely at some point while work is being carried out
·If working near broken lines, they should be isolated and earthed at a safe distance either side of the working area
If you find yourself near any broken power lines, there are some vital safety measures to follow:
·If you are in a vehicle that has touched a wire it’s safer to stay in the vehicle. If there are additional hazards (such as fire) that mean you need to get out of the vehicle, jump out of it as far as you can and try to land with both feet together to avoid step potential (see below).
·Don’t touch the vehicle whilst standing on the ground as it has probably retained a substantial electrical charge. A shock received in this way is called “touch potential” (see below).
·Don’t return to the vehicle until it’s been confirmed that it’s safe to do so.
·Call the emergency services and tell them your location, what has happened and that electricity wires are involved. Ask them to contact the line’s owner.
·If you’re close to, or in contact with, a damaged wire, move away as quickly as possible by shuffling and keeping both feet on the ground or by jumping with both feet together.
·If you see such an accident occur, do not approach within 10 metres of the broken line until the lines’ owner says it is safe to do so.
Step Potential – voltage is higher nearer the source – as you step away one foot may be in contact with lower voltage than the other foot. The electrical current will flow through your body as you lift one foot and arc back to earth delivering a shock that’s 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.