Lightning and Surge Protection

Protection concept

A lightning protection system consists of external lightning protection – air termination systems, down conductors and an earthing system that guide the lightning current to earth in a controlled way – and internal lightning protection, which uses equipotential bonding and coordinated surge protective devices to shield sensitive electrical and electronic equipment from induced voltage spikes. The appropriate lightning protection level and extent of surge protection follow from a risk analysis that considers building occupancy, local lightning strike frequency and the potential for consequential loss.

Common weaknesses

Frequent deficiencies include interrupted or corroded down conductors, missing equipotential bonding for later installations such as photovoltaic or air conditioning systems, and incompletely coordinated surge protection that shields only the main distribution board while leaving downstream sub-distribution boards and end devices unprotected.

Insurance relevance

Lightning strike is one of the four classic perils of fire insurance; inadequate lightning and surge protection increases both the probability of fire and the frequency of costly electronic equipment losses. For exposed locations, risk engineers check recurring inspections of the lightning protection system and documentation of the protection level as part of the risk survey.