What is the primary purpose of a lightning arrestor?

The primary purpose of a lightning arrestor is to provide low impedance to ground. This device is crucial in protecting electrical systems and structures from the damaging effects of lightning strikes. When a lightning bolt strikes, the arrestor channels the excessive voltage and current away from the protected system and safely into the ground, thereby preventing equipment damage or fire hazards. By ensuring low impedance, the lightning arrestor minimizes the resistance encountered by the lightning current, allowing it to flow through the device and into the ground efficiently.

Other options do not align with the function of a lightning arrestor. Increasing voltage or regulating current are functions that pertain to different devices, such as transformers or regulators, which manage voltage levels and current flow under standard operating conditions. Disconnecting circuits typically involves circuit breakers or switches, which serve a different role in controlling electrical flow rather than protecting against electrical surges from lightning. Thus, the emphasis on providing a low impedance path to ground is the key reason why this option is the correct one.