Which of the following is a common feature of surge protectors?

A common feature of surge protectors is that they have indicator lights to show the protection status. These lights are essential for users to determine whether the surge protector is functioning correctly and whether it is providing the necessary protection for connected devices.

Surge protectors work by diverting excess voltage away from connected electronics during a power surge, such as during a lightning strike or a sudden increase in electrical power. The indicator lights on these devices serve as a visual cue, letting users know if the protector is active and capable of defending against surges. If a light indicates that the device is no longer functional, it alerts the user to replace the surge protector before any critical equipment is connected, ensuring continued protection.

In contrast, while surge protectors do not increase voltage output, convert AC to DC power, or specifically enhance the energy efficiency of devices, their primary purpose is to safeguard electronic devices from voltage spikes. The absence of features like voltage output enhancement or voltage conversion disqualifies them from claiming the other characteristics mentioned.