What does 'step potential' refer to?

'Step potential' refers to the voltage difference experienced when a person stands with their feet apart during an electrical fault condition, such as a ground fault. When a fault occurs, current may flow through the ground, creating a voltage gradient. This means there is a difference in voltage between points on the ground. If a person has their feet spaced apart, they can experience a difference in potential between their two feet, as one foot may be at a higher voltage than the other due to this gradient. This can be extremely dangerous, as it can lead to electrical shock if sufficient voltage exists between the feet.

Option A focuses on voltage differences between substations, which is not related to the concept of step potential. Option C describes differences between energized wires, which is about voltage but does not relate to a person’s interaction with ground potential. Option D concerns voltage differences in overhead lines, which again does not pertain to the situation of standing on the ground and does not cover the human factor involved in step potential.