Surge protection device (SPD)
Also called: spd, surge protector, surge arrester, transient voltage suppressor, surge protection
A surge protection device (SPD) is a protective component fitted in the distribution board that clamps a sudden voltage spike and diverts its energy safely to earth before it reaches your wiring and appliances. The spikes it guards against are *transients* — over-voltages lasting only microseconds, thrown off by grid switching, large motors starting and stopping, or a lightning strike nearby (it needs no direct hit). An SPD does a different job from the other devices in the board: an MCB trips on too much current (overload or short) and an RCD/ELCB trips on earth-leakage to prevent shock, while an SPD reacts to a voltage spike — so it complements them rather than replacing them. For a home full of electronics (TVs, computers, smart-home gear, AC control boards) it is cheap insurance against the one surge that fries several devices at once. Fitting one is a consumer-unit job for a licensed electrician in Dubai; protection-device makers such as Hager publish the SPD types and ratings used.
Related terms
Distribution board (DB)
The panel of breakers that splits your home's power into separate circuits — the first place to look when something trips.
MCB (miniature circuit breaker)
The switch in your board that trips to cut power when a circuit is overloaded or short-circuits.
RCD / ELCB (residual current device)
The safety device that trips in milliseconds if current leaks to earth — the one that protects you from a fatal shock.
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