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Static electricity may build up on both materials and people. When a charged
person approaches flammable gases or vapours and a spark ignites the substance, the
resulting explosion or fire often causes serious injury.

Figure 14.5 - Prevention of static discharge – container connected to
earthed drum.

Lightning strikes are a natural form of static electricity and result in large
amounts of electrical energy being dissipated in a short time in a limited space with a
varying degree of damage. The current produced in the vast majority of strikes
exceeds 3000 amps over a short period of time. Before a strike, the electrical
potential between the cloud and earth might be about 100 million volts and the
energy released at its peak might be about 100 million watts per metre of strike.
The need to provide lightning protection depends on a number of factors,
which include:
 the risk of a strike occurring;
 the number of people likely to be affected;
 the location of structure and the nearness of other tall structures in the
vicinity;
 the type of construction, including the materials used;
 the contents of structure or building (including any flammable substances);
 the value of the building and its contents.
Expert advice will be required from a specialist company in lightning
protection, especially when flammable substances are involved. Lightning strikes can
also cause complete destruction and/or signifi cant disruption of electronic
equipment.

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