Page 25 - Electrical Safety of Low Voltage Systems

Basic Definitions and Nomenclature 7

FIGURE 1.7 In TT systems, ECPs are directly connected to the ground,
independently of the grounding of any point of the power supply system.
1.2.25 Touch Voltage
The touch voltage V T is defined as the voltage differential, which a
person may be subject to, between both hands and both feet.

1.2.26 Prospective Step Voltage
The prospective step voltage V SS is defined as the potential difference
between two points on the surface of the earth, displaced by the dis-
tance of 1 m, when the earth is not being touched by the person.

1.2.27 Step Voltage
The step voltage V S is defined as the potential difference, which a per-
son may be subject to, between the two feet, conventionally displaced
by1m.