What must portable or movable equipment static ground wires be large enough to carry?

• A. Maximum fault current
• B. Expected current load
• C. Short-circuit rating
• D. Ambient temperature rating

Answer: (B)

Grounding conductors on portable or movable equipment are sized to handle the current that can realistically flow through the grounding path during normal use, so that static charges can be safely discharged without overheating the wire or losing a solid grounding connection. In explosive safety contexts, keeping a reliable ground path is crucial to prevent static buildup from reaching ignition sources, and that requires a conductor gauge that can carry the expected load continuously.

The other factors relate to different situations. A fault current is the surge that can occur during a short circuit, which is handled by protective devices and other design considerations, not the routine grounding path during normal operation. The short-circuit rating concerns the equipment’s ability to withstand a fault, not the ongoing current in the grounding conductor. Ambient temperature rating affects insulation and environmental limits, not the continuous current-carrying capability of the grounding path.