What is the primary purpose of surge-protective devices (SPDs)?

The primary purpose of surge-protective devices (SPDs) is to protect electrical devices from surges. Electrical surges are sudden increases in voltage that can occur due to various factors such as lightning strikes, power outages, or sudden changes in electrical load. These surges can cause significant damage to sensitive electronic equipment, leading to potential failures, data loss, or even fire hazards.

SPDs are designed to detect these surges and divert the excess voltage away from connected devices, thus safeguarding them from potential harm. By absorbing or redirecting the surge energy, SPDs ensure that the voltage levels remain within safe limits, effectively extending the lifespan of electrical equipment and maintaining the integrity of the electrical system.

This focus on protection distinguishes SPDs from other potential functions implied by the other choices. For instance, allowing more voltage would not align with the purpose of preventing damage. Enhancing power supply distribution or reducing installation costs could be benefits of using SPDs indirectly, but these are not their primary function.