Zs Calculator

Use the Zs Calculator to predict the earth fault loop impedance (Zs) of a circuit, given that the external earth fault loop impedance (Ze, or Zdb), and the resistance of the line and circuit protective conductors (R1+R2) are known.

This app can also be used to predict the R1+R2 value of a circuit, if the Ze and Zs measurements are known.

Please note this app is NOT a substitute for taking measurements, and calculated results may differ from measured due to parallel earth paths not considered by the app. Measured results should always be taken by a suitably qualified person with the relevant technical knowledge and experience to carry out the job safely, using a calibrated measurement device.