Loop Impedance: Calculation

While physical testing with a loop impedance meter is common, calculation is vital during the design phase. It allows engineers to specify the correct cable sizes and protection before a single wire is laid, preventing costly retrofits or safety failures once the building is powered.

$$Z_{loop} = R_{loop} + jX_{loop}$$

The loop impedance is calculated as the sum of individual impedances along the fault path. The fundamental equation is: loop impedance calculation