# Cable short circuit fault current calculator AS/NZS 3008

The calculator calculates the short circuit fault current at a specified distance in a cable run, based on the source short circuit fault current level.

## See Also

- Cable Sizing Calculator AS/NZS 3008
- AC and DC Voltage Drop Calculator with Formulas and Examples AS/NZS 3008

## Parameters

**Voltage (V):**Specify the voltage and select the phase arrangement: 1 Phase AC or 3 phase AC. Currently supports AC only.**Source fault current (kA)**: Specify the prospective fault current of the switchboard that the load is supplied from.**Standard cable size:**Select a standard cable size in mm^{2}as defined in AS/NZ 3008.**Distance (m, ft):**Specify the estimated cable length in meters of feet.

## How to calculate the Cable short circuit fault current?

- Cable short circuit fault current calculator calculates the single and three phase load fault current as follows:
- \(I_{1\phi-load-fault}=\dfrac{V_{source}} {(Z_{source}+2\cdot Z_{cable})}\)
- \(I_{3\phi-load-fault}=\dfrac{V_{source}} {(Z_{source}+\sqrt{3}\cdot Z_{cable})}\)
- The source impedance is calculated as:
- \(Z_{source}=\dfrac{V_{source}} {I_{sourcefault}}\)
- The cable impedance is calculated as:
- \(Z_{cable} = \sqrt{R_{cable}^2 + X_{cable}^2}\). This method calculates the impedance for the worse case power factor, i.e. when the cable and load power factor is the same.
- The cable short circuit fault current calculator uses the resistance \(R_{cable}\) from Table 35 in AS/NZS 3008 at 75°C , and the reactance values \(X_{cable}\) from Table 30 in AS/NZS 3008 for multi-core PVC circular conductors.

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