Good grounds are essential for the proper operation of which device?

Good grounds are essential for the proper operation of lightning arrestors. Lightning arrestors are devices designed to protect electrical systems from the high-voltage surges caused by lightning strikes. They do this by directing the surge safely into the ground, where it can dissipate without harming the electrical equipment connected to that system.

A good grounding system is crucial because it ensures the lightning arrestor can effectively channel the surge. If the grounding is inadequate, the arrestor may not function properly, potentially leading to equipment damage or electrical failures. Therefore, the effectiveness of lightning arrestors is heavily dependent on solid and reliable grounding practices, making good grounds indispensable for their operation.

While the other devices listed, such as fuses, transformers, and circuit breakers, may also require grounding for safety and operational effectiveness, their primary functions do not hinge on grounding in the same critical way as lightning arrestors.