7. Leakage current meters

7.1 Principle of leakage current measurement and its limitations

This measure concerns equipment supplied by an electrical distribution whose reference point, i.e. generally the neutral, is connected to earth ground, i.e. types TN and TT. In such a case, the sum of the instantaneous currents i ₁ + i ₂ + i ₃ supplying the receiving equipment is zero, except in the case of an insulation fault giving rise to a leakage current i _f whose instantaneous value will be i _f = i ₁ + i ₂ ...