Surge Protection Devices for 18th Edition 

Two forms of surge - LEMP - Lighting Electro Magnetic Pulse & SEMP - Switching Electro Magnetic Pulse

To be clear, SPDs do not protect an installation from lighting strikes, only a fitted lighting protection system to BS EN 62305 will prevent a direct strike from damaging the property.

Surges are short-term high voltage impulses often called ‘spikes’, ‘transients’ or ‘glitches’. The duration of these surges are typically measured in micro seconds. Surges are typically produced from internal tripping events such as a lift motor in a hotel or office, lighting being turned on and off. When there is a high energy inrush, this generates a surge and continues on around the circuits and can damage sensitive electronic equipment.