Electrician's Licensing Practice Exam

In commercial installations, a 400 amp service typically requires two ground wires. This configuration is essential due to the increased load and the need for redundancy to ensure safety and compliance with the National Electrical Code (NEC) requirements. One ground wire is often used as the equipment grounding conductor, which connects to the metal parts of the equipment to facilitate a low-resistance path for fault currents. The second ground wire may be used to connect the grounding system to ground rods or other grounding points, ensuring that there is a reliable and effective path for fault currents to dissipate safely into the earth. This redundancy ensures that if one ground wire becomes compromised due to damage or wear over time, the second wire still provides adequate grounding, minimizing the risk of electrical shock or fire hazards. This practice enhances overall safety and reliability in high-capacity electrical systems like a 400 amp service.