Introduction to Health and Safety at Work

Introduction to Health and Safety at Work
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material. Insulation is often accompanied by the enclos-
ure of the live conductors so that they are out of reach 
to people. A breakdown in insulation can cause electric 
shock, fi re, explosion or instrument damage.
Isolation
The isolation of an electrical circuit involves more than 
‘switching off’ the current in that the circuit is made 
dead and cannot be accidentally re-energized. It, there-
fore, creates a barrier between the equipment and the 
electrical supply which only an authorized person should 
be able to remove. When it is intended to carry out work, 
such as mechanical maintenance or a cleaning operation 
on plant or machinery, isolation of electrical equipment 
will be required to ensure safety during the work pro-
cess. Isolators should always be locked off when work 
is to be done on electrical equipment.
Before earthing or working on an isolated circuit, 
checks must be made to ensure that the circuit is dead 
and that the isolation switch is ‘locked off’ and clearly 
labelled.
Reduced low voltage systems
When the working conditions are relatively severe either 
due to wet conditions or heavy and frequent usage of 
equipment, reduced voltage systems should be used.
All portable tools used on construction sites, vehicle 
washing stations or near swimming pools, should operate 
on 110 V or less, preferably with a centre tapped to earth 
at 55 V. This means that while the full 110 V are available to 
power the tool, only 55 V are available to shock the worker. 
At this level of voltage, the effect of any electric shock 
should not be severe. For lighting, even lower voltages can 
be used and are even safer. Another way to reduce the 
voltage is to use 
battery (cordless) operated hand tools.