Which component is critical for preventing follow-up line current in a lightning arrester?

The correct answer focuses on the importance of having a low resistance path to earth in a lightning arrester system. Lightning arresters are designed to protect electrical equipment from high-voltage surges caused by lightning strikes. When a lightning strike occurs, the arrester diverts the surge to a grounding system, allowing it to safely dissipate into the earth.

A low resistance path to earth is critical because it ensures that the energy from the lightning strike can flow away rapidly and efficiently. If the path to ground has high resistance, it could lead to inadequate dissipation of the surge energy, potentially allowing dangerous follow-up line currents to affect adjacent equipment or structures. This is essential for maintaining the integrity and safety of the electrical system.

In contrast, other components such as high resistance would impede the flow of surge current, an insulation layer primarily serves to separate conductive components and does not directly influence current flow during a surge, and a damping device focuses on controlling oscillations rather than directly addressing line current that follows a lightning strike. These alternatives do not fulfill the same critical role as a low resistance path to earth in preventing follow-up line currents.