Calculate maximum permitted Zs values (earth loop impedance) as per BS7671, also includes temperature adjusted values.
Using the picker wheel select the protective device (fuses, MCBs, RCBOs) and device rating to calculate the maximum permitted Zs value for your selected device.
+ BS7671 Amendment 3 2015 values
+ BS EN devices
+ Ze + R1+R2 = Zs
+ 100% values
+ 80% values
+ 0.4 second disconnection times
+ 0.2 second disconnection times
+ 5 second disconnection times
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