Electrical Safety

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Electricity can kill. Each year about 1000 accidents at work involving electric shock or burns are reported to the Health and Safety Executive (HSE). Aproximately 30% of these accidents are fatal. Most of these fatalities arise from contact with overhead or underground power cables.

However, even shocks that don't result in death can cause severe and permanent injury. People who have received a shock from defective or faulty equipment have been known to fall from ladders, scaffolds or other work platforms. And those using electricity may not be the only ones at risk: poor electrical installations and faulty electrical appliances can lead to fires which may also cause death or injury to others. With careful planning and common-sense precautions, most of these accidents can be avoided.

This is an outline of basic measures you can use to help you control the risks from your use of electricity particularly in the workplace. If you have any questions or concerns, your local Health and Safety inspector will have more information about safety issues and your legal obligations.

What are the hazards?

The main hazards are:

contact with live parts causing shock and burns (two hundred and thirty volts AC, normal mains voltage, can be lethal);
faults which could be the cause of a fire;
fire or explosion where electricity could be the source of ignition in a potentially flammable or explosive atmosphere, eg in a petrol station.

Assessing the risk

Hazard means anything which can cause harm.

Risk is the chance that someone will actually be hurt by the hazard in some way.

The initial stage in the process of controlling risk is to carry out a risk assessment in order to identify what needs to be done. (This is a legal requirement for all risks at work.)

When carrying out a risk assessment:

identify the hazards;
decide who might be harmed, and how;
evaluate the risks arising from the hazards and decide whether existing precautions are adequate or more should be taken;
if you have five or more employees, record any significant findings;
review your assessment from time to time and revise it if necessary.

The risk of injury from electricity is strongly linked to where and how it is used. The risks are greatest in harsh conditions, for example:

in wet surroundings - unsuitable equipment can easily become live and can make its surroundings live;
out of doors - equipment may not only become wet but may be at greater risk of damage;
in cramped spaces with a lot of earthed metalwork, such as inside a tank or bin - if an electrical fault developed it could be very difficult to avoid a shock.

There is more risk associated with certain pieces of equipment than there is with others. Extension leads are particularly vulnerable to damage - to their plugs and sockets, to their electrical connections, and to the cable itself. Other flexible leads, particularly those connected to equipment which is frequently moved around can also be affected by similar problems. More information on carrying out risk assessments is available in HSE publications.

Reducing the risk

Once the risk assessment has been completed, you can use the data you have collected to reduce objectionable risks from electrical equipment in the workplace. There are many things you can do to achieve this; here are some.

Ensure that the electrical installation is safe
install new electrical systems to a suitable standard, eg BS 7671 Requirements for electrical installations, and then maintain them in a safe condition;
existing installations should also be properly maintained;
provide enough socket-outlets - overloading socket-outlets by using adaptors can cause fires.
provide safe and suitable equipment
use equipment that has been chosen for its suitability for the particular working environment;
sometimes electrical risks can be eliminated by using air, hydraulic or hand-powered tools. These are especially useful in harsh conditions;
ensure that equipment is safe when supplied and then maintain it in a safe condition;
provide an accessible and clearly identified switch near each fixed machine to cut off power in an emergency;
for portable equipment, use socket-outlets which are close by so that equipment can be easily disconnected in an emergency;
the ends of flexible cables should always have the outer sheath of the cable firmly clamped to stop the wires (particularly the earth) pulling out of the terminals;
replace damaged sections of cable completely;
use proper connectors or cable couplers to join lengths of cable. Do not use strip connector blocks covered in insulating tape;
some types of equipment are double insulated. These are often marked with a 'double-square' symbol
the supply leads have only two wires - live (brown) and neutral (blue). Make sure they are properly connected if the plug is not a moulded-on type;
protect lightbulbs and other equipment which could easily be damaged in use. Electric shock is a possibility if they break;
engineers should craft electrical equipment found in flammable/explosive atmospheres so that said equipment aids in halting ignition. You might need to talk to a specialist.

Reduce the voltage

One of the best ways of reducing the risk of injury when using electrical equipment is to limit the supply voltage to the lowest needed to get the job done, such as:

temporary lighting can be run at lower voltages, eg 12, 25, 50 or 110 volts;
where electrically powered tools are used, battery operated are safest;
portable tools are readily available which are designed to be run from a 110 volts centre-tapped-to-earth supply.

Provide a electrical safety device

If equipment operating at 230 volts or higher is used, an RCD (residual current device) can provide additional safety. The RCD is in place to detect faults in the system and turns off the power supply if one is found. They are able to detect some, but not all faults. The best place for an RCD is built into the main switchboard or the socket-outlet, as this means that the supply cables are permanently protected. If this is not possible a plug incorporating an RCD, or a plug-in RCD adaptor, can also provide additional safety.

The RCDs for the protection of people have a rated tripping current (also known as sensitivity) of not more than 30 milliamps (mA for short).

Remember:

an RCD is a valuable safety device, never bypass it;
if the RCD trips, it is a sign there is a fault. Check the system before using it again;
if the RCD trips frequently and no fault can be found in the system, consult the manufacturer of the RCD;
the RCD has a test button to check that its mechanism is free and functioning. Use this regularly.

Carry out preventative maintenance

To prevent danger it is important that all equipment and installations be maintained. It is highly advisable to include a proper plan of visual examination as well as electrical safety testing if needed. By focusing on a straightforward, inexpensive system of looking for visible signs of damage or faults, most of the electrical risks can be controlled. This will need to be backed up by testing as is necessary

Fixed installations are also recommended to be inspected and tested periodically by a competent person.

The frequency of inspections and any necessary testing will depend on the type of equipment, how often it is used, and the environment in which it is used. Records of the results of inspection and testing can be useful in assessing the effectiveness of the system.

Users of equipment can contribute by reporting any problems or damage.

Work safely

It is advised that you thoroughly evaluate the people who deal with electricity and make sure that they are competent to do so. Even relatively simple tasks such as wiring a plug can lead to danger - ensure that people know exactly what they are doing before they start.

Check that:

suspect or faulty equipment is taken out of use, labelled "DO NOT USE" and kept secure until examined by a competent person;
where possible, tools and power socket-outlets are switched off before plugging in or unplugging;
equipment is switched off and/or unplugged before cleaning or making adjustments.

Many tasks, like repairs, require special expertise, and should not be handled by amateurs. Tasks like those should only be tackled by people with a detailed understanding of the risks and the precautions needed.

You must not allow work on or near exposed live parts of equipment unless it is absolutely unavoidable and suitable precautions have been taken to prevent injury, both to the workers and to anyone else who may be in the area.

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