Which distinction is critical between step voltage and touch voltage?

The correct distinction between step voltage and touch voltage is that step voltage occurs over distances, while touch voltage is associated with an instantaneous electrical potential difference between grounded surfaces and a person's body when in contact.

Step voltage arises when a person is standing on the ground and a voltage gradient exists, causing a potential difference between their feet. This potential difference can affect the person over the distance from their feet to the ground, which can lead to hazardous situations if they are near energized equipment. It's crucial to understand that this type of voltage is measured across a space, making it relevant to the distance between two points on the ground.

On the other hand, touch voltage is specifically the voltage that a person experiences at a given moment when they touch an object that is at a different electrical potential, typically caused by contact with energized equipment or surfaces.

This distinction is fundamental for safety practices because understanding how these types of voltages operate helps in designing safety protocols and grounding practices to mitigate the risks associated with electrical shock.