TC 78

IEC 61472-2:2020 specifies a method for determining the electrical component of the minimum approach distances for live working, for AC systems 1 kV up to and including 72,5 kV. This document addresses system overvoltages and the working air distances between equipment and/or workers at different potentials.
The withstand voltage and minimum approach distances determined by the method described in this document can be used only if the following working conditions prevail:

• workers are trained for, and skilled in, working live lines or close to live conductors or equipment;
• the operating conditions are adjusted so that the statistical overvoltage does not exceed the value selected for the determination of the required withstand voltage;
• transient overvoltages are the determining overvoltages;
• tool insulation has no continuous film of moisture present on the surface;
• no lightning is observed within 10 km of the work site;
• allowance is made for the effect of the conducting components of tools.