Methodology
Each verification case below is a self-contained engineering scenario. For each scenario we publish the inputs, the calculator output, the hand-calculation result and whether the two agree. We re-run these tests every time the calculator's lookup tables or calculation logic is updated. The Node.js spot-check script lives in the project repo at tools/cable-sizing/test/spotcheck.mjs.
Where the calculator output differs from the hand-calculation by more than ± 1 standard cable size, we investigate. Differences within 1 size typically reflect rounding in install-method derating factors or breakpoints in the standard cable size series (e.g. 25 mm² vs 35 mm²).
Scenario set v1.1 (Cu XLPE, Cu PVC, Cu EPR 110°C)
1. 100 A 3-phase sub-main, Cu XLPE multi-core, on tray spaced, 30 m
Inputs: Ib = 100 A, V = 400 V 3ph, Cu XLPE 4c, install = unenc_spaced, ambient = 40°C, grouping = 1, length = 30 m, VD limit = 5%
Hand-calc: derate 1.00, required Iz = 100 A. Smallest cable: 25 mm² (119 A). VD = 1.61 mV/A.m × 100 A × 30 m × 0.9 / 1000 = 4.35 V = 1.09% < 5%. Earth: 6 mm² per AS/NZS 3000 Table 5.1. PASS
Calculator: 25 mm² Cu XLPE multi-core, Iz 119 A, VD 1.09% — MATCH
2. 200 A 3-phase sub-main, Cu XLPE multi-core, on tray spaced, 50 m
Inputs: Ib = 200 A, V = 400 V 3ph, Cu XLPE 4c, install = unenc_spaced, ambient = 40°C, grouping = 1, length = 50 m, VD limit = 5%
Hand-calc: required Iz = 200 A. Smallest cable: 70 mm² (229 A). VD = 0.609 mV/A.m × 200 × 50 × 0.9 / 1000 = 5.48 V = 1.37%. Earth: 25 mm². PASS
Calculator: 70 mm² Cu XLPE multi-core, Iz 229 A, VD 1.37% — MATCH
3. 32 A 1-phase final sub-circuit, Cu PVC multi-core, enclosed conduit, 30 m, 35°C
Inputs: Ib = 32 A, V = 230 V 1ph, Cu PVC 2c, install = enc_in_air, ambient = 35°C, grouping = 1, length = 30 m, VD limit = 5%
Hand-calc: ambient derate ~1.05 for PVC at 35°C, required Iz = 32/1.05 = 30.5 A. Smallest cable: 4 mm² (PVC 2c ~38 A enclosed in air) gives derated 39.9 A. VD at 4 mm² PVC ~10 mV/A.m, Vd = 10 × 32 × 30 / 1000 = 9.6 V = 4.2%. PASS for VD but tight on capacity, may want 6 mm² for margin. Earth: 2.5 mm². PASS
Calculator: 6 mm² Cu PVC multi-core (calculator picks one size above for margin), VD 2.55% — CONSERVATIVE MATCH (1 size larger for safety)
4. 63 A 3-phase final, Cu XLPE multi-core, 4 grouped circuits, on tray touching
Inputs: Ib = 63 A, V = 400 V 3ph, Cu XLPE 4c, install = unenc_touching, ambient = 40°C, grouping = 4, length = 20 m, VD limit = 5%
Hand-calc: ambient = 1.00, grouping = 0.75, required Iz = 63 / 0.75 = 84 A. 16 mm² (83 A touching) gives derated 83 × 0.75 = 62 A < 63 A FAIL. Step up to 25 mm² (111 A × 0.75 = 83 A) >= 63 A PASS. VD at 25 mm² ~1.61 mV/A.m, Vd = 1.61 × 63 × 20 × 0.9 / 1000 = 1.83 V = 0.46%. Earth: 6 mm². PASS
Calculator: 25 mm² Cu XLPE multi-core, Iz 83 A, VD 0.46% — MATCH
5. 250 A 3-phase sub-main, Cu XLPE multi-core, 2 parallel cables, on tray spaced, 60 m
Inputs: Ib = 250 A, V = 400 V 3ph, Cu XLPE 4c, install = unenc_spaced, ambient = 40°C, grouping = 1, length = 60 m, VD limit = 5%, parallel = 2
Hand-calc: per cable current = 125 A, derate 1.00, required per-cable Iz = 125 A. Smallest: 35 mm² (147 A spaced). Total capacity 294 A. VD = 1.17 mV/A.m × 125 (per cable) × 60 × 0.9 / 1000 = 7.9 V = 1.97%. Earth: 10 mm² (per Cl 5.3.3.1.1 still based on single active CSA, not parallel total). PASS
Calculator: 2 × 35 mm² Cu XLPE multi-core, Iz total 294 A, VD 1.97% — MATCH
6. 100 A 3-phase IT load (non-linear, > 15% 3rd harmonic), 30 m
Inputs: Ib = 100 A, V = 400 V 3ph, Cu XLPE 4c, install = unenc_spaced, ambient = 40°C, grouping = 1, length = 30 m, VD limit = 5%, harmonic = nonlinear
Hand-calc: harmonic derate 0.84, required Iz = 100/0.84 = 119 A. 25 mm² (119 A) just meets. VD same as scenario 1 = 1.09%. Neutral sized full to active = 25 mm². PASS
Calculator: 25 mm² Cu XLPE multi-core (neutral 25 mm² full size), Iz 100 A (derated by 0.84), VD 1.09% — MATCH
Known limitations (transparent disclosure)
- Aluminium cables not yet supported. The Nexans Olex 2017 Handbook covers Al aerial cables only. Aluminium power cable data will come in v1.2 once we source from another current AS/NZS 3008.1.1-derived secondary source.
- R+X separation not performed. Voltage drop uses the combined Vc value from AS/NZS 3008.1.1 (which assumes pf = 0.8 lagging). At low pf with long runs, the calculator may under-report VD by 5-15%. To add safety margin, specify a tighter %VD limit (e.g. 4%).
- Cable temperature correction not iterated. AS/NZS 3008.1.1 Cl 4.4 allows VD adjustment when the cable runs below rated operating temperature (under-loaded). Calculator uses the table mV/A.m as-is, which is conservative.
- Earth fault loop impedance disconnection-time NOT checked. The earth conductor is sized per AS/NZS 3000 Table 5.1 Method 1, but Zs × Ia ≤ Uo per Cl B2 is the responsibility of the designer. CCC verifies this manually on every cert.
- No discrimination / selectivity check. Upstream <> downstream protective device coordination is out of scope.
- No short-circuit fault rating check. Cable adiabatic compliance against system fault current must be verified separately.
- No motor starting / inrush sizing. Calculator sizes for steady-state continuous current only.
- No AS/NZS 3013 fire-rated cabling support. Essential services (EWIS, FIP, smoke control, lift fire mode) cables must be sized using manufacturer fire-rated cable tables.
Data source audit trail
- Cable current rating tables: Nexans Olex 2017 Handbook (Australia), pages 60-86, extracted to CSV with full audit headers (source page, extraction date, raw-row count) at
tools/cable-sizing/data/olex-2017/ in the project repo.
- Voltage drop mV/A.m values: same source.
- Ambient + grouping derating factors: AS/NZS 3008.1.1 well-known values (Tables 22, 27) embedded in the calculator code.
- Earth conductor sizing: AS/NZS 3000:2018 Table 5.1 Method 1.
- Voltage drop limit: AS/NZS 3000:2018 Clause 3.6.2 (5% combined).
- Harmonic neutral / capacity derate: AS/NZS 3008.1.1 Appendix B.6.
- Parallel cable requirements: AS/NZS 3000:2018 Clause 3.4.4.
- Protective device sizing: AS/NZS 3000:2018 Clause 2.5.3.1 (Ib ≤ In ≤ Iz).
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