Why does underground cable rated above 5000 volts require a grounded shield?

A grounded shield for underground cables rated above 5000 volts is essential for dissipating electrical stress that builds up due to the high voltages present. This shielding provides a pathway for any induced or stray voltages to safely divert to the ground, reducing the risk of electrical breakdown within the cable insulation and ensuring the continued safe operation of the system. By managing electrical stress, the grounded shield helps to prevent insulation failure, which is critical in maintaining cable integrity and reliability in high-voltage applications. Proper grounding of the shield plays a significant role in enhancing the overall safety and performance of the electrical system.

While physical protection, signal strength, and overheating are important considerations in various contexts, they do not specifically address the crucial function of the grounded shield in managing electrical stress, which is why the selection focuses on that aspect.