Engineering calculator
Earthing conductor sizing (adiabatic)
Minimum conductor cross-section to withstand an earth fault for a given duration.
Inputs
Results
- Minimum cross-section
- 174.8mm²
- Next standard size
- 185mm²
S = I × √t / k
Safety-critical result — professional verification required
This is a screening estimate. It must not be used for design, equipment selection, protection settings or PPE without verification by a suitably qualified and competent engineer using a full study.
Assumptions
- Adiabatic heating (no heat loss during the fault)
- k = 143 is typical for PVC-insulated copper starting at 30 °C; use the k value for your material, insulation and temperature limits
Limitations
- Conductor sizing only — does not verify touch/step voltages or grid resistance
- Backup protection clearing time should be used for grid conductors
References: AS/NZS 3000 · IEEE 80 · AS 2067
Provided for general information. Gridlinks Solutions accepts no liability for decisions made using this calculator without independent engineering verification.
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