IEC 60364-5-52 Cable Sizing — Method
IEC 60364-5-52 (Wiring Systems — Selection and Erection) is the international standard adopted by every IEC member state — directly in Europe (HD 60364-5-52), Asia, Africa and South America, and as the basis of national wiring rules in BS 7671, AS/NZS 3008 and others. The procedure is: derate the table ampacity for ambient temperature (Ca), grouping (Cg) and thermal insulation (Ci); pick the smallest cable whose corrected ampacity Iz exceeds the design current Ib.
Where:
- Ib — design current of the circuit (A), from the load calculation
- Ca — ambient temperature correction (1.00 at 30 °C reference)
- Cg — grouping / bunching factor (1.00 for a single circuit)
- Ci — thermal-insulation factor (1.00 if the cable is in free air; 0.50 if fully buried in insulation)
Then pick the smallest cable cross-section in IEC 60364-5-52 Table B.52.4 whose tabulated ampacity Iz ≥ It.
Related cable sizing calculators
Other standard- and method-specific cable-sizing calculators in the same series — same procedure, different reference tables and defaults:
- Cable Sizing Calculator (universal) — the seed page covering all standards in one tool
- BS 7671 Cable Sizing Calculator — BS 7671:2018+A2 · UK / NICEIC
- AS/NZS 3008 Cable Sizing Calculator — AS/NZS 3008.1.1 · Australia / New Zealand
- Copper Cable Sizing Calculator — Copper · Cu Conductor
- All Electrical Engineering Calculators →
Frequently Asked Questions
For copper conductors with PVC (70°C) insulation use Table B.52.2; for XLPE/EPR (90°C) insulation use Table B.52.4. Each row gives the tabulated current Iz for sizes 1.5–630 mm² × Reference Methods A1, A2, B1, B2, C, D1, D2, E, F, G. The Iz values are at 30°C ambient, no grouping — derate for actual conditions.
IEC 60364-5-52 defines reference methods A1/A2 (insulated conductors / cables in conduit in thermally insulated wall), B1/B2 (in conduit or trunking on wall), C (clipped direct on a wall or ceiling), D1/D2 (in ground in conduit / direct buried), E (free air, clipped to perforated tray), F (free air, multi-core spaced) and G (free air, single-core touching). The reference method determines which Iz column to read.
Multiply the tabulated Iz by all applicable correction factors: Iz_corrected = Iz_table × Ca × Cg × Ci. Ca = ambient temperature (Table B.52.14, e.g. 0.87 at 40°C for XLPE), Cg = grouping factor (Table B.52.17, e.g. 0.80 for 3 circuits touching), Ci = thermal insulation factor (0.5 if cable passes fully through insulation > 0.5 m). Then verify Iz_corrected ≥ Ib.
Annex G recommends ≤ 3 % for lighting circuits and ≤ 5 % for other uses, measured between the origin of the installation and the load. Some countries adopt stricter limits (e.g. UK BS 7671 keeps the 3 % / 5 % values; Germany VDE 0100-520 follows IEC). Voltage drop at consumer connections to the public network must not exceed the values agreed with the DNO.
Short-circuit thermal sizing is covered in IEC 60364-4-43 and IEC 60364-5-54 with the adiabatic equation S² ≥ I²·t / k², where k = 115 (PVC Cu), 143 (XLPE Cu), 76 (PVC Al), 94 (XLPE Al). The minimum cable size selected for ampacity must also satisfy this short-circuit withstand check during the protective device's clearing time.
Functionally yes — HD 60364-5-52 is the CENELEC harmonisation document, which transposes IEC 60364-5-52 into European national standards (DIN VDE 0100-520, NF C 15-100, NEN 1010, etc.). Each national code may add country-specific notes, but the ampacity tables and methodology are identical.