Scope
This part of IEC 61472 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.
NOTE In some countries, special procedures have been developed to permit live working with surface moisture on tools at
distribution voltages (below 50 kV).