Surge protective device

Also known as SPD

A surge protective device is a protective electrical device that limits transient overvoltage so a surge is less likely to damage connected equipment.

A surge protective device, often shortened to SPD, is a protective electrical device that limits transient overvoltage so a surge is less likely to damage connected equipment. ABB describes SPDs as protection for electrical installations and connected devices from transient overvoltages, while Phoenix Contact notes that PV systems, inverters, battery storage systems and cables can suffer damage from overvoltage. IET model electrical forms include SPD type fields and notes for T1, T2 and T3 devices, so the wording can appear in consumer-unit schedules, certificates and home-energy installation paperwork.