What is the purpose of surge protection devices (SPDs) in installation design?

• A. To regulate current in the circuit
• B. To reduce energy consumption
• C. To monitor grid frequency
• D. To limit voltage surges from external sources (e.g., lightning) to protect sensitive equipment

Answer: (D)

Surge protection devices are used to limit transient voltage spikes on electrical systems. They work by clamping or diverting surge energy away from sensitive equipment, typically directing it to ground or neutral, so the voltage reaching connected devices stays within safe levels. This is especially important for surges caused by external events like lightning or utility switching. By keeping voltage transients under control, SPDs reduce the risk of insulation damage, arcing, nuisance tripping, and premature equipment failure. They do not regulate current, reduce energy consumption, or monitor grid frequency, which is why protecting equipment from voltage surges is the correct purpose.