Earthing Conductor Sizing
Calculate the minimum conductor cross-section required to withstand the prospective fault current. Choose between the IEEE Std 80-2013 thermal formula (Eq. 37) or the IEC 60364-5-54 adiabatic method. Compare all standard sizes and generate a report.
Sizing Method & Inputs
Standard Size Comparison
at 20 kA for 0.5 s| Size | Diameter | Max Fault Current | Status |
|---|---|---|---|
| 10 mm² | ∅ 3.57 mm | 2.60 kA | Fail |
| 16 mm² | ∅ 4.51 mm | 4.17 kA | Fail |
| 25 mm² | ∅ 5.64 mm | 6.51 kA | Fail |
| 35 mm² | ∅ 6.68 mm | 9.11 kA | Fail |
| 50 mm² | ∅ 7.98 mm | 13.02 kA | Fail |
| 70 mm² | ∅ 9.44 mm | 18.22 kA | Fail |
| 95 mm²REC | ∅ 11.00 mm | 24.73 kA | Pass |
| 120 mm² | ∅ 12.36 mm | 31.24 kA | Pass |
| 150 mm² | ∅ 13.82 mm | 39.05 kA | Pass |
| 185 mm² | ∅ 15.35 mm | 48.16 kA | Pass |
| 240 mm² | ∅ 17.48 mm | 62.48 kA | Pass |
| 300 mm² | ∅ 19.54 mm | 78.09 kA | Pass |
| 400 mm² | ∅ 22.57 mm | 104.13 kA | Pass |
| 500 mm² | ∅ 25.23 mm | 130.16 kA | Pass |
Minimum Required Area
76.8
mm²
∅ 9.89 mm equivalent solid
Standard Size (next up)
95
mm²
∅ 11.00 mm
At Recommended Size (95 mm²)
IEEE 80-2013
Uses Equation 37 from IEEE Std 80-2013, accounting for material-specific thermal capacity (TCAP), resistivity, and temperature coefficients. Ambient temperature assumed at 40°C; maximum temperature based on material (copper: 1084°C, steel: 419°C).
Guidance only — verify with a chartered engineer before installation.
IEEE 80 method per IEEE Std 80-2013, Equation 37. Adiabatic method per IEC 60364-5-54 Table 54.1 and BS 7430:2011+A1:2015. K values assume adiabatic heating — conservative for fault durations up to ~5 s.
This tool provides design guidance only. Results should be confirmed by a chartered engineer against site-specific data and applicable project standards.
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