Prospective fault current calculator
Compare line–neutral and line–earth fault-current estimates from separate loop impedances.
Result
Prospective fault current– – –
Enter your values and press Calculate result.I = RMS voltage ÷ complete loop impedanceSingle-phase sinusoidal steady-state model with constant source voltage and complete loop impedance magnitudes. The two impedances are distinct inputs. Excludes three-phase faults, DC offset, peak current, source dynamics and changes in impedance. These estimates do not establish a protective device rating or replace a site assessment.
What the numbers mean
Each fault path needs its own complete source-and-return impedance. Earth loop impedance cannot stand in for line–neutral loop impedance. The higher result compares only these two entered scenarios; it is not the maximum of every possible fault condition.
Formula reference: Fluke · 1670 series loop and fault-current measurements ↗A worked example
230 V ÷ 0.1 Ω gives a line–neutral estimate of 2,300 A. A separate 230 V ÷ 0.5 Ω line–earth loop gives 460 A. The higher of these two estimates is 2.3 kA.
Validation, precision and limitations