Surge protective devices (SPDs) are primarily designed to safeguard electrical systems and personnel from the danger of transient overvoltages caused by lightning.
SPDs are a fundamental requirement for compliance with BSEN 62305:2011 in addition to Structural Protection.
To satisfy BSEN62305 R1 risk, “loss of life”, all services entering or leaving a structure and from any roof mounted equipment, must be provided with suitable SPDs. This typically involves the main supply, telephone and data cables, cctv, pv arrays and external lighting, signage or remote structures fed separately from the main distribution board.
Risk R2 “loss of service to the public” dictates the need for further SPDs in the form of coordinated surge protection. This is generally protection of individual services within different zones of a structure. For instance, an internal sub distribution board feeding a communications room in an ambulance station, or individual SPDs to individual computers or important electronic equipment within a hospital, in order to offer a second line of defence.
It is therefore recognised that danger exists not only from a direct strike to a structure from a lightning discharge of up to 200KA, but indirect strikes causing havoc to internal electrical equipment costing thousands in unnecessary and avoidable loss of production and insurance claims.