What is the purpose of surge protection devices and where are they installed?

• A. To limit transient overvoltages; installed at service entrance and on critical equipment or panels.
• B. To increase voltage for motors; installed in motor leads only.
• C. To monitor current; installed on every branch circuit.
• D. To provide grounding; installed at the main ground rod.

Answer: (A)

Surge protection devices are meant to limit transient overvoltages that can travel through an electrical system, protecting equipment from damage and nuisance failures. They work by giving surge energy a low-impedance path to divert it away from sensitive circuits, usually using components like metal-oxide varistors or similar devices that clamp voltage to a safe level during a surge.

Installing them at the service entrance helps protect the entire building by intercepting surges as soon as they enter the system. Placing additional protection on critical equipment or panels provides targeted defense for particularly sensitive or costly gear, such as computers, PLCs, or drives, ensuring that remaining surge energy is attenuated right where those loads are connected.

Surge protectors don’t increase voltage, monitor current, or provide grounding. They are protective devices that work alongside proper grounding to suppress abnormal transient voltages.