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Electrical injuries are not only caused by contact with a high voltage, lower voltages under certain circumstances can also cause serious injury, for example the batteries contained in a UPS back up power supply system. However the risk of injury is generally greater with higher voltages but in all cases other circumstances including the route of the electricity through the body dictates the severity of the injury.
Human contact with electricity is not the only hazard electrical sparks from batteries and mobile phones for example could ignite flammable substances.
Alternating current (AC) and Direct Current (DC) electrical supplies can cause a range of injuries including:
- Electric shock
- Electrical burns
- Loss of muscle control
- Thermal burns
Under UK law the Health and Safety at Work Act 1974 in Great Britain or the Health and Safety at Work (Northern Ireland) Order 1978, employers are responsible for ensuring the safety and health of their employees and members of the public, if they are at risk from work activities. These laws include electrical safety.
When working with or near electricity in a building like this, there are many risks.
You may not be allowed to work without a permit or supervision, no matter how small the job is. In this room we have high voltage electricity and very powerful back up power supplies called UPS units that store power in batteries in the case of power cuts. Even when to power is off they can give a life threatening shock.
We are now going to look at some guidelines for safe working with and near electricity or electrical equipment. Firstly you should complete a risk assessment for the work you are planning, and make sure this covers electrical hazards. Learn how to recognise electrical wires. These may be overhead power lines, electrical wiring in a workplace, or cables buried under the ground. Look for electrical wires, cables or equipment near where you are going to work and check for signs warning of dangers from electricity, or any other hazard. there may be a map of the electrical services in the area but always be aware of hazards not on the map.
Remember to always look up, down, and around you for cables. If you will be digging or disturbing the earth or cutting into surfaces, use a cable locator to find buried services and permanently mark the position of electrical services you find. Work away from electrical wiring wherever possible. If you have to work near electrical wiring or equipment, ask for the electrical supply to be turned off. When you have been told it is off, make sure the power is off, and cannot be turned on again without you agreeing.
If the electrical supply cannot be turned off, consult a competent person who should be able to advise you on the best way to proceed. Identify where it is safe to work. Put up danger notices where there are still live electrical circuits, and warn your co-workers where it is safe to work and where it is not safe. Remember to remove notices at the end of the work. There are different electrical danger signs including Danger of death electricity and warning - Isolate supply before opening cover.
Signs warning of electrical danger may not always be easy to see, or may have been removed, so even if you see no signs, electrical cables may still be nearby. Stay vigilant. When you see signs warning of electrical danger it is highly likely there is electricity present. Remember, you don’t need to touch a high voltage cable to get an electric shock and even low voltage cables can be dangerous.
If you cannot work out where the electricity is, ask a competent person to do it for you. You may not see electrical wires near where you plan to work but this doesn’t mean there aren’t any. Even if you do see wires, there may be others you cannot see. Electrical wiring may sometimes look like pipes, and may be a range of colours.
Before you drill or start cutting into surfaces:
If the electrical power has been turned off to allow you to do work safely, it is essential that the power stays off until you have finished work.
Make sure YOU are in control and STAY in control. A good way is to have the only key to the switch or a locked room or cabinet containing the switch.
Remember, if you remove a fuse, someone could inserted one in its place, and remember some people ignore notices. If you have any doubts that the electricity may be turned on again without your knowledge and consent, STOP WORK.