HSE Guide
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HSE
Guidance on Electrical Safety - reproduced here for information
Electricity
can kill. Each year about 1000 accidents at work involving electric
shock or burns are reported to the Health and Safety Executive (HSE).
Around 30 of these are fatal. Most of these fatalities arise from
contact with overhead or underground power cables.
Even non-fatal
shocks can cause severe and permanent injury. Shocks from faulty
equipment may lead to falls from ladders, scaffolds or other work
platforms. 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. Most
of these accidents can be avoided by careful planning and straightforward
precautions.
This leaflet
outlines 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 and burns (normal mains voltage,
230 volts AC, can kill);
- faults which
could cause fires;
- fire or
explosion where electricity could be the source of ignition in
a potentially flammable or explosive atmosphere, eg in a spray
paint booth.
Assessing
the Risk
Hazard means
anything which can cause harm.
Risk is the
chance, great or small, that someone will actually be harmed by
the hazard.
The first stage
in 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.
Some items
of equipment can also involve greater risk than others. Extension
leads are particularly liable 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 moved a great deal, can suffer from similar problems.
More information
on carrying out risk assessments is available in other HSE publications.
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 place of
work. 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
- choose equipment
that is suitable for its working environment;
- electrical
risks can sometimes 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. There is a risk of electric shock if they are broken;
- electrical
equipment used in flammable/explosive atmospheres should be designed
to stop it from causing ignition. You may need specialist advice.
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 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 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.
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 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
All electrical
equipment and installations should be maintained to prevent danger.
It is strongly recommended that this includes an appropriate system
of visual inspection and, where necessary, testing. By concentrating
on a simple, 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 necessary.
It is recommended
that fixed installations are 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.
Equipment users
can help by reporting any damage or defects they find.
Work
safely
Make sure that
people who are working with electricity are competent to do the
job. Even simple tasks such as wiring a plug can lead to danger
- ensure that people know 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.
More complicated
tasks, such as equipment repairs or alterations to an electrical
installation, should only be tackled by people with a knowledge
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.
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. Service plans should be available
from regional electricity companies, local authorities, highways
authorities, etc.
Overhead
power 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. Over half of the fatal electrical
accidents each year are caused by contact with overhead lines. More
detailed guidance on avoidance of danger from overhead electric
lines is available from HSE.
Electrified
railways and tramways
If 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.
HSE
Guidance on Electrical Safety
The following
publications contain advice on the safe use of electricity for particular
industries or in high risk circumstances.
Risk
assessment and general health and safety
- 5 steps
to risk assessment IND(G)163L*
- Essentials
of health and safety at work ISBN 0 7176 0716 X
- Maintenance
of portable electrical equipment
- Maintaining
portable and transportable electrical equipment HS(G)107 ISBN
0 7176 0715 1
- Maintaining
portable electrical equipment in offices and other low-risk environments
IND(G)160L*
- Maintaining
portable electrical equipment in hotels and tourist accommodation
IND(G)164L*
General
electrical guidance
- Live rails
kill - advice for people who need to work near live conductor
rails IND(G)150L*
- Avoiding
danger from underground services HS(G)47 ISBN 0 7176 0435 7
- Avoidance
of danger from overhead electrical lines GS6(rev) ISBN 0 11 885668
5
- Electrical
safety on construction sites HS(G)141 ISBN 0 7176 1000 4
- Electricity
at work - safe working practices HS(G)85 ISBN 0 7176 0442 X
- Electrical
test equipment for use by electricians GS38(rev) ISBN 0 7176 0845
X
- Electrical
safety at places of entertainment GS50 ISBN 0 11 885598 0
- Electrical
hazards from steam/water pressure cleaners etc PM29(rev) ISBN
0 7176 0813 1
- Selection
and use of electric handlamps PM38 ISBN 0 11 886360 6
- Memorandum
of guidance on the Electricity at Work Regulations 1989 HS(R)25
ISBN 0 11 883963 2
GUIDANCE ON
ELECTRICAL SAFETY FROM OTHER ORGANISATIONS
Note: The inspection
and testing intervals for electrical equipment given in these publications
are recommendations and are not legal requirements.
BS 7671: 1992
Requirements for electrical installations . IEE Wiring Regulations
16th edition. The IEE Wiring Regulations have the status of a British
Standard. They are supported by a separate series of Guidance Notes
enlarging on particular requirements of parts of the Regulations.
Code of practice
for in-service inspection and testing of electrical equipment
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