Zs

Zs calculates the maximum Zs for MCB B, MCB C and MCB D Type Circuit Breakers

For fault protection, the limiting values of earth fault loop impedances, Zs are given in BS 7671.

This app is perfect for helping you with commissioning, reviewing test sheets, witnessing electrical testing and even with cable design!

Earth fault loop impedance (Zs) is the impedance in ohms of the circuit path formed during a fault between earthed metal work and live parts. It includes the external impedance circuit (Ze) and the resistance of the phase and circuit protective conductors (R1 + R2).