risks from electricity
What are the risks from electricity?
Harm can be caused to any person when they are exposed to ‘live parts’ that are either touched directly or indirectly by means of some conducting object or material. Voltages over 50 volts AC or 120 volts DC are considered hazardous.
Electricity can kill. Each year about 1000 accidents at work involving electric shocks or burns are reported to the Health and Safety Executive (HSE). Around 30 of these are fatal, most of them arising from contact with overhead or underground power cables.
Shocks from faulty equipment can cause severe and permanent injury and can also lead to indirect injuries, due to falls from ladders, scaffolds, or other work platforms.
Faulty electrical appliances can also lead to fires. As well as causing injuries and loss of life, fires cause damage to plant, equipment and property.
WHO IS MOST AT RISK FROM ELECTRICITY?
Anyone can be exposed to the dangers of electricity while at work and everyone should be made aware of the dangers.
Those most at risk include maintenance staff, those working with electrical plant, equipment and machinery, and people working in harsh environments such as construction sites.
Most electrical accidents occur because individuals:
- are working on or near equipment which is thought to be dead but which is, in fact, live
- are working on or near equipment which is known to be live, but where those involved are without adequate training or appropriate equipment, or they have not taken adequate precautions
- misuse equipment or use electrical equipment which they know to be faulty.
ASSESSING THE RISKS FROM ELECTRICITY
Consider the following hazards in your risk assessment:
Live parts Normal mains voltage, 230 volts AC, can kill. Also, contact with live parts can cause shocks and burns.
Fire Electrical faults can cause fires. This is particularly true where the equipment contains a heat source (e.g. heaters, including water heaters, washing machines, ovens, heat-seal packaging equipment).
Flammable or explosive atmospheres Electricity can be a source of ignition in a potentially flammable or explosive atmosphere, e.g. in spray paint booths or around refuelling areas.
Where and how electricity is used The risks from electricity are greatest in harsh conditions.
In wet conditions, unsuitable equipment can easily become live and can make its surroundings live.
While outdoors, equipment may not only become wet but may be at greater risk of damage.
In cramped with a lot of earthed metalwork, such as inside tanks, ducts and silos, if an electrical fault develops it can be very difficult to avoid a shock.
Types of equipment in use Some items of equipment can also involve greater risk than others. Extension leads are particularly liable to damage to their plugs and sockets, cables, and electrical connections. Other flexible leads, particularly those connected to equipment that is moved a great deal, can suffer from similar problems.
BASIC ELECTRICAL SAFETY
Below are some minimum steps you should take to ensure electrical safety.
- install new electrical systems to BS 7671 Requirements for Electrical Installations
- maintain all electrical installations in good working order
- provide enough socket-outlets for equipment in use
- avoid overloading socket-outlets – using adaptors can cause fires
- provide an accessible and clearly identified switch (‘Emergency Off’ or ‘EMO’ button) near fixed machinery to cut off power in an emergency
- for portable equipment, connect to nearby socket-outlets so that it can be easily disconnected in an emergency.
Use the right equipment
- choose electrical equipment that is suitable for its working environment
- ensure that equipment is safe when supplied and maintain it in a safe condition
- electrical equipment used in flammable/explosive atmospheres should be designed not to produce sparks. Seek specialist advice when choosing this type of equipment.
- protect light bulbs and other easily damaged equipment – there is a risk of electric shock if they are broken.
Maintenance and repairs
- ensure equipment is fitted with the correctly rated fuse.
- ensure cable ends always have their outer sheaths firmly clamped to stop wires working loose from plugs or inside equipment
- replace damaged sections of cable completely – never repair cuts with insulating tape.
- use proper connectors to join lengths of cable – don’t use connector blocks covered in insulating tape or ‘splice’ wires by twisting them together
- some equipment is 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 all wires are connected securely if the 13A plug is not a moulded-on type.
Use other forms of power where possible Electrical risks can sometimes be eliminated by using air, hydraulic or hand-powered tools. These are especially useful in harsh conditions, but remember they could introduce other hazards.
Reduce the voltage Using lower voltages can reduce or eliminate the risks of electric shocks and burns:
- portable tools are available which can be run from a 110 volts, centre-tapped-to-earth supply, (usually from a transformer)
- where electrically powered tools are used, battery-operated are safest
- temporary lighting can be run at lower voltages, e.g. 12, 25, 50 or 110 volts.
Use Residual Current Devices (RCDs) for extra safety An RCD can provide additional safety. An RCD detects some (but not all) faults in the electrical system and rapidly switches off the supply.
The best place for an RCD is built into the main supply or the socket-outlet, as this means that the supply cables are permanently protected.
If this is not possible, use a plug incorporating an RCD or a plug-in RCD adaptor. RCDs for protecting people have a rated tripping current (sensitivity) of not more than 30 milliamps (mA).
- 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
- use the RCD test button regularly to check that its mechanism is free and functioning
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