Introduction to Health and Safety at Work

12.3.4 Electric 
arcing
A person who is standing on earth too close to a high 
voltage conductor may suffer fl ash burns as a result of 
arc formation. Such burns may be extensive and lower 
the resistance of the skin so that electric shock may add 
to the ill effects. Electric arc faults can cause temporary 
blindness by burning the retina of the eye and this may 
lead to additional secondary hazards. The quantity of 
electrical energy is as important as the size of the voltage 
since the voltage will determine the distance over which 
the arc will travel. The risk of arcing can be reduced by 
the insulation of live conductors.
Strong electromagnetic fi 
elds induce surface 
charges on people. If these charges accumulate, skin 
sensation is affected and spark discharges to earth may 
cause localized pain or bruising. Whether prolonged 
exposure to strong fi elds has any other signifi cant effects 
on health has not been proved. However, the action of an 
implanted cardiac pacemaker may be disturbed by the 
close proximity of its wearer to a powerful electromag-
netic fi eld. The health effects of arcing and other non-
ionising radiation are covered in Chapter 15.
12.3.5 Static 
electricity
Static electricity is produced by the build-up of elec-
trons on weak electrical conductors or insulating mater-
ials. These materials may be gaseous, liquid or solid and 
may include fl ammable liquids, powders, plastic fi lms 
and granules. The generation of static may be caused by 
the rapid separation of highly insulated materials by fric-
tion or by transfer from one highly charged material to 
another in an electric fi eld by induction (see Figure 12.5).
Discharges of static electricity may be suffi cient to 
cause serious electric shock and are always a potential 
source of ignition when fl 
ammable liquid, dusts or 
powders are present. Flour dust in a mill, for example, 
has been ignited by static electricity.
Static electricity may build up on both materials and 
people. When a charged person approaches fl ammable 
gases or vapours and a spark ignites the substance, the 
resulting explosion or fi re often causes serious injury.
Lightning strikes are a natural form of static electri-
city and result in large amounts of electrical energy being 
Figure 12.5
Prevention of static discharge – container 
connected to earthed drum.

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