External Ground Bus Bar requirements specify what characteristics?

• A. Sized just for the primary transmission line; 1/8 inch thickness
• B. Minimally sized to accommodate all transmission lines and other grounding connections; 1/4 inch minimum thickness
• C. Oversized for future expansion; 1/2 inch thickness
• D. No minimum thickness required

Answer: (B)

External ground bus bars must be sized so they can physically and electrically accommodate all grounding conductors and bonding connections from the equipment and the structure, not just a single line. This ensures a low-impedance, reliable return path for fault currents and keeps all grounds bonded together in one common point. The minimum thickness of 1/4 inch provides the necessary mechanical strength and current-carrying capability to support multiple conductors and grounding clamps without bending, damage, or loosening over time, while avoiding unnecessary bulk. Choosing a bus that is only sized for the primary line would crowd or exclude other grounding connections, and using a thinner than minimum bus would compromise durability and safety. An oversized, overly thick bus isn’t required and adds unnecessary weight and cost.