Which term describes the network that ties all equipment grounding in a substation to earth?

• A. Ground Fault Relay
• B. Grounding Grid
• C. Bonding Strap
• D. Ground Rod

Answer: (B)

The main idea is the interconnected system that ties all equipment grounding conductors to earth at a substation. This grounding grid is a mesh of buried conductors and sometimes electrodes that together provide a single, low-impedance path for fault currents to reach the earth. By connecting all metal parts through this grid, it keeps equipment at the same potential and helps limit dangerous voltage differences during faults, which also helps protective devices clear faults reliably.

That’s why grounding grid is the best term. A ground fault relay is a protective device that detects current leaking to earth, not the earth-tie network itself. A bonding strap bonds individual pieces of equipment to reduce potential differences locally, but it doesn’t describe the whole earth-return network. A ground rod is an electrode used to establish grounding, but the network involves many conductors and connections forming a grid, not a single rod.