Surge Protective Device (SPD)
A device designed to protect electrical equipment from voltage spikes (surges) caused by lightning, power grid switching, or other transient events.
Detailed Explanation
NEC Article 285 covers SPD installation. As of the 2020 NEC (230.67), Type 1 or Type 2 SPDs are required at the service for all dwelling unit services. SPDs work by diverting surge energy to the grounding system. Type 1 devices are installed before the main overcurrent device, Type 2 at the panelboard, and Type 3 at individual outlets. SPDs protect sensitive electronics like computers, smart home systems, and appliances from damaging voltage spikes.
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