Introduction to Health and Safety at Work

Electrical hazards and control
195
of electric burns should be available to all people working 
on electrical equipment and their supervisors.
A 
management system
should be in place to 
ensure that the electrical systems are installed, operated 
and maintained in a safe manner. All managers should 
be responsible for the provision of adequate resources of 
people, material and advice to ensure that the safety of 
electrical systems under their control is satisfactory and 
that 
safe systems of work
are in place for all electrical 
equipment. (Chapter 6 gives more information on both 
safe systems of work and permits-to-work.)
For small factories and offi ce or shop premises 
where the system voltages are normally at mains voltage, 
it may be necessary for an external competent person 
to be available to offer the necessary advice. Managers 
must set up a high voltage permit-to-work system for all 
work at and above 600 V. The system should be appropri-
ate to the extent of the electrical system involved. 
Consideration should also be given to the introduction of 
a permit system for voltages under 600 V when appropri-
ate and for all work on live conductors.
The additional control measures that should be 
taken when working with electricity or using electrical 
equipment are summarized by the following topics:
➤
the selection of suitable equipment
➤
the use of protective systems
➤
inspection and maintenance strategies.
These three groups of measures will be discussed in 
detail.
12.5 
The selection and suitability of 
equipment
Many factors which affect the selection of suitable elec-
trical equipment, such as fl ammable, explosive and damp 
atmospheres and adverse weather conditions, have 
already been considered. Other issues include high or 
low temperatures, dirty or corrosive processes or prob-
lems associated with vegetation or animals (for example, 
tree roots touching and displacing underground power 
cables, farm animals urinating near power supply lines 
and rats gnawing through cables). Temperature extremes 
will affect, for example, the lubrication of motor bearings 
and corrosive atmospheres can lead to the breakdown 
of insulating materials. The equipment selected must be 
suitable for the task demanded or either it will become 
overloaded or running costs will be too high.
The equipment should be installed to a recognized 
standard and capable of being isolated in the event of 
an emergency. It is also important that the equipment is 
effectively and safely earthed. Electric supply failures may 
affect process plant and equipment. These are certain to 
happen at some time and the design of the installation 
should be such that a safe shut-down can be achieved 
in the event of a total mains failure. This may require the 
use of a battery backed shut-down system or emergency 
stand-by electric generators (assuming that this is cost 
effective).
Finally, it is important to stress that electrical 
equipment must only be used within the rating perform-
ance given by the manufacturer and any accompanying 
instructions from the manufacturer or supplier must be 
carefully followed.