Solid grounding has what impact on fault currents and arc-flash risk?

Solid grounding has what impact on fault currents and arc-flash risk?

• A. Very high fault currents and increased arc-flash risk.
• B. Very low fault currents and reduced arc-flash risk.
• C. Moderate fault currents; no arc-flash risk.
• D. It prevents faults entirely.

Answer: (A)

Solid grounding directly ties the system neutral to earth, giving a path of very low impedance for faults. When a line-to-ground fault occurs, the current can surge to a very high level because the fault current isn’t limited much by impedance; it’s mainly the source and the small remaining line impedance. That large fault current drives more energy into any arc that forms, raising the incident energy and the arc-flash risk to personnel. The idea that fault currents would be very low or that arc-flash risk would be eliminated or faults would be prevented isn’t correct for solid grounding, since the low impedance that helps clear faults quickly also allows large fault currents and higher arc energy.

Solid grounding directly ties the system neutral to earth, giving a path of very low impedance for faults. When a line-to-ground fault occurs, the current can surge to a very high level because the fault current isn’t limited much by impedance; it’s mainly the source and the small remaining line impedance. That large fault current drives more energy into any arc that forms, raising the incident energy and the arc-flash risk to personnel. The idea that fault currents would be very low or that arc-flash risk would be eliminated or faults would be prevented isn’t correct for solid grounding, since the low impedance that helps clear faults quickly also allows large fault currents and higher arc energy.