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Electrical Safety
Introduction
Electricity can kill or severely injure people and can cause damage to property. Every year many accidents at work involving electric shock or burns are reported to the Health and Safety Executive (HSE). Most of the fatal incidents are caused by contact with overhead power lines.
Even non-fatal shocks can cause severe and permanent injury. For example, shocks from faulty equipment may lead to falls from ladders, scaffolds or other work platforms. Those using or working with electricity may not be the only ones at risk – poor electrical installations and faulty electrical appliances can lead to fire, which may also cause death or injury to others. Most of these accidents can be avoided by careful planning and straightforward precautions.
This training provides some basic measures to help you control the risks from your use of electricity at work.
What are the Hazards?
The main hazards are:
- Contact with live parts causing shock & burns – normal mains voltage (230v AC) can kill.
- Faults which could cause fire.
- Fire or explosion – where electricity could be the source of ignition in a potentially flammable or explosive atmosphere.
Assessing the Risk
A Risk Assessment will help to identify any risks associated with electricity and will help you decide what action you need to take to use any electrical installations and equipment safely. 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.
- Outdoors – 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 – if an electrical fault developed it could be very difficult to avoid a shock.
Some items of equipment can also involve greater risk than others. E.g., extension leads are particularly liable to damage to their plugs, sockets, connections and the cable itself. Other flexible leads, particularly those connected to equipment which is often moved can suffer from similar problems.
Reducing the Risk
Once you have completed the risk assessment, you can use your findings to reduce unacceptable risks from the electrical equipment in your workplace. There are many things you can do to achieve this, and some of them are listed below.
Ensure you are ‘competent’ for the task
Competent means having suitable training, skill, and knowledge for the task to prevent injury to yourself and others.
Ensure the electrical installation is safe
Make sure that:
- New electrical systems are installed to a suitable standard, e.g., ‘BS 7671 Requirements for electrical installations’ and then maintain them in a safe condition.
- Existing installations are maintained in a safe condition.
- There are enough socket outlets – overloading socket outlets by using adaptors can cause fire.
Use safe and suitable equipment
- Choose equipment that is suitable for its working environment.
- Consider using air, hydraulic or hand-powered tools which are useful in harsh conditions.
- Make sure equipment is safe before use and is maintained in a safe condition.
- Identify locations and accessibility of emergency power cut-off switches.
- For portable equipment, use socket outlets which are close by so that equipment can be easily disconnected in an emergency.
- To stop wires (particularly the earth) pulling out of terminals, ensure the ends of flexible cables have the outer sheath of the cable firmly clamped.
- 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 moulded.
- Protect light bulbs and other equipment which could easily be damaged in use.
- In potentially flammable or explosive atmospheres, only use special electrical equipment designed for these areas. If required gain specialist advice.
Reduce the voltage
One of the best ways to reduce the risk of injury when using electrical equipment is to limit the supply voltage to the lowest needed. Examples include:
- Running temporary lighting at lower voltages, e.g., 12, 25, 50 or 110 volts.
- Where possible use battery operated tools instead of electrically powered ones.
- Alternatively, use portable tools designed to be run from a 110-volt centre-tapped-to-earth supply.
Provide a safety device
If equipment operating at 230 volts or higher is used, an RCD (Residual Current Device) can provide additional safety. An RCD is a device which detects some, but not all faults in the electrical system and rapidly switches off the supply.
The best place for an RCD is in 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.
RCDs for protecting people have a rated tripping current (sensitivity) of not more than 30 milliamps (mA). Remember:
- An RCD is a valuable safety device, never bypass it.
- If it trips, it is a sign there is a fault – check the system before using it again.
- If it trips frequently and no fault can be found in the system, consult the manufacturer.
- The RCD has a test button to check its mechanism is free and functioning – you should use this regularly.
Carry out preventative maintenance
All electrical equipment, including portable equipment and installations, should be maintained (so far as reasonably practicable) to prevent danger. This is a requirement of the Electricity at Work Regulations 1989.
Safety checks should be made based on the risk of electrical items becoming faulty. There is an increased risk of faults occurring if the equipment is not used correctly, is not suitable for the job or is used in a harsh environment.
An appropriate system of maintenance can include:
- A pre-use check for loose cables or signs of fire damage.
- Inspection to check inside the plug for internal damage, bare wires and correct fuse used.
- Where necessary, a Portable Appliance Test (PAT).
Damaged or defective equipment should be removed from use and either repaired by someone competent or disposed of to prevent its further use.
Work safely
Before working with electricity make sure you are competent to do the job. Even simple tasks such as wiring a plug can lead to danger – ensure you know what you are doing.
Check that:
- Suspect or faulty equipment is taken out of use, labelled ‘DO NOT USE’ and kept secure until examined by a competent person.
- Tools and power socket outlets are switched off before plugging in or unplugging.
- Equipment is switched off and/or unplugged before cleaning or adjusting.
Equipment repairs or alterations to an electrical installation should only be carried out by people with knowledge of the risks and the precautions needed.
You must not work on or near exposed, live parts of equipment unless it is unavoidable and suitable precautions have been taken to prevent injury to everyone concerned.
Underground power cables
Always assume cables will be present when digging in the street, pavement or near buildings. Use up-to-date service plans, cable avoidance tools and safe digging practice to avoid danger.
Overhead power lines
Over half of the fatal electrical accidents each year are caused by contact with overhead lines. When working near overhead lines, it may be possible to have them switched off if the owners are given enough notice. If this cannot be done, consult the owners about the safe working distance from the cables.
Remember that electricity can flash over from overhead lines even though plant and equipment do not touch them.
Electrified railways and tramways
If you are working near electrified railways or tramways, consult the line or track operating company. Remember that some railways and tramways use electrified rails rather than overhead cables.
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