How to Calculate Earth Fault Loop Impedance for a Circuit

In this Q&A video, we explain how to calculate Earth Fault Loop Impedance (Zs) for an electrical circuit step-by-step. Learn: ✅ What Earth Fault Loop Impedance is and why it matters. ✅ The components of the fault loop and how impedance affects circuit safety. ✅ How to apply BS7671 regulations and calculate Zs using Ze and (R1 + R2). ✅ Real-world examples with a 50A Type B MCB and 10 mm² cable in a 9 kW boiler circuit. This video is part of our electrical design training series in collaboration with BG Electrical. Missed part one? Start here 👉 https://training.efixx.co.uk/course/introduction-to-electrical-design-cpd-in-association-with-bg-electrical Further Electrical Design training 👉 https://training.efixx.co.uk/course/further-electrical-design-in-association-with-bg-electrical ============== Time Stamps ⏱ 00:00 What is earth fault loop impedance? 02:20 Why do we care about it? 04:30 How quickly will our circuit need to disconnect? 05:50 Calculating earth fault loop impedance 07:00 Finding the Ze 08:13 R1 & R2 values 09:40 Final calculation 10:20 Will this trip our circuit in the required time? 12:25 validate your learning! ============== #earthfault #electricalinstallation #electricaldesign