Why are lightning arresters necessary at the end of underground primary lines?

Lightning arresters are essential at the end of underground primary lines primarily to prevent equipment damage. When lightning strikes, it can send a surge of electrical energy through the power lines, which can lead to excessive voltage and currents that can adversely affect transformer equipment, switches, and other components. Lightning arresters work by diverting this surge into the ground, thereby protecting both the infrastructure and the electrical equipment connected to the underground lines.

While it's true that enhancing performance and complying with safety codes are important considerations in the installation and maintenance of electrical systems, the primary function of lightning arresters specifically pertains to the protection against damage caused by electrical surges, making prevention of equipment damage the most relevant reason for their necessity.