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The whole nature of how electrical equipment is used in homes and at work has evolved; with
everyday activities relying on electronic equipment. Products such as computers, printers,
flat screen televisions, industrial control equipment such as PLC’s, alarms, microwaves and
washing machines are common place. These can all be vulnerable to transient overvoltages,
which can significantly reduce the equipment’s lifespan through degradation and damage.
This guide expands upon some of the requirements found in the 17
th
Edition of the IET Wiring Regulations and other
standards, related to the protection of electrical equipment from electrical surges. It considers protection against voltage
transients on the electrical installation only. Consideration should also be given to the protection against transient
overvoltages transmitted by data transmission systems. BS EN 50174 refers.
Note: this guide does not ensure compliance with BS 7671 or indeed guarantee that equipment is protected against electrical
surges. The electrical specifier should use their own judgment, consulting BS 7671 and the BS EN 62305 series (protection
against lightning) to determine the need and correct selection of surge protection devices.
Introduction