What best describes touch potential vs step potential hazard near outdoor HV sources?

• A. Touch potential is the voltage you could experience by touching a live surface; step potential is the potential difference between your feet; both can cause shock if not controlled
• B. Touch potential only applies to indoor equipment
• C. Step potential is irrelevant to safety
• D. Both are measured by insulation resistance testing

Answer: (A)

Touch potential and step potential describe two ways current can travel through a person around energized outdoor high-voltage sources. Touch potential is the voltage difference between the live surface you’re touching and the ground you’re standing on; if you grab a live component, current can flow through your body to the ground. Step potential is the voltage difference between your two feet as you stand or move, due to a ground potential gradient in the soil near the energized equipment; this can drive current up one leg and down the other. Both scenarios create a real shock risk near outdoor HV sources, especially when the source is not isolated or properly shielded, or when the ground is conductive and moisture present. So the description that captures both ideas and notes they can cause shock if not controlled is the best match.

Other choices miss the mark because touch potential isn’t limited to indoor equipment and step potential is a genuine safety concern near HV sources, not irrelevant. And insulation resistance testing measures insulation integrity, not the potential differences that cause bodily current paths in the ground or through a person.