Wire gauge calculator Italian electrical

The Italian wire gauge calculator sizes the conductor per CEI 64-8 V8 eighth edition 2024 norm "Low voltage electrical installations up to 1000 V AC and 1500 V DC". The single-phase voltage drop formula: ΔV = (2 × L × I × ρ × cosφ) / S in volts, where L is length in meters, I current in amperes, ρ resistivity (copper 0.0178 Ω·mm²/m at 20°C, aluminum 0.0283), S section in mm² and cosφ power factor typically 0.9 residential.

Three-phase: ΔV = (√3 × L × I × ρ × cosφ) / S.

Voltage drop percentage ΔV% = (ΔV / Vn) × 100 where Vn = 230 V single-phase Italian domestic or 400 V three-phase industrial (previously 220/380 V harmonized European CENELEC HD 472 S1 1988). Italian limits CEI 64-8 art. 525.1: lighting 3% max, other uses 4% max; standard commercial sections 1.5 - 2.5 - 4 - 6 - 10 - 16 - 25 - 35 - 50 - 70 - 95 - 120 - 150 - 185 - 240 - 300 - 400 mm² (CEI EN 60228:2007 conductors).

AWG American Wire Gauge → mm² European conversion: 14 AWG = 2.08 mm² (≈2.5); 12 AWG = 3.31 (≈4); 10 AWG = 5.26 (≈6); 8 AWG = 8.37 (≈10); 6 AWG = 13.3 (≈16); 4 AWG = 21.2 (≈25); 2 AWG = 33.6 (≈35); 1/0 AWG = 53.5 (≈50); 4/0 AWG = 107 (≈95). The American AWG system was invented in 1857 by J.R. Brown of Brown & Sharpe Manufacturing Providence Rhode Island; base formula AWG = -39 × log(d/0.005) / log(92) + 36 where d is diameter in inches.

Italian electrical cable industry is European leader: Prysmian Group Milan 1872 ex-Pirelli Cables (40 plants worldwide, 12 bn € revenue 2023, world leader submarine cables Western Link UK 600 km laid 2017), Cavicel Pomarance Pisa 1972, ICEL Caltignaga Novara 1949 (LV residential leader Lombardy 30%), Tratos Cavi Pieve Santo Stefano Arezzo 1966, Italtel Settimo Milanese 1921 telecommunications.

Italian wire sizing tables

(Source: Italian CEI 64-8/5 Table 52H capacity unipolar PVC insulated cables installation B1 in conduit + CEI EN 60228:2007 + CEI EN 60364-5-52:2011).

Italian voltage drop examples

• Single-family villa Brescia Lombardy ENEL 6 kW: meter at gate, panel inside house 60 m. Inom = 6,000 / (230 × 0.9) = 29 A single-phase. Cable FG7OR 0.6/1 kV Prysmian Milan buried 50 cm depth PVC sheath (CEI 11-17). 16 mm² copper section: ΔV = (2 × 60 × 29 × 0.0178 × 0.9) / 16 = 3.49 V = 1.5% (within 4% CEI 64-8)
• Vicenza Veneto workshop three-phase 22 kW: main panel line 80 m. Inom = 22,000 / (1.732 × 400 × 0.85) = 37.4 A. FG7OM1 35 mm² laid in aerial tray (CEI 20-22 II): ΔV = (1.732 × 80 × 37.4 × 0.0178 × 0.85) / 35 = 2.24 V = 0.56%
• Rome Lazio Tesla Wall Connector wallbox 7.4 kW single-phase: Type 2 socket at garage 25 m from panel. Inom = 32 A. Cable 6 mm² + BTicino Salvavita Bergamo MCB 32 A C32 + Type A or B 30 mA RCD (CEI 64-8 V8 art. 722). ΔV = (2 × 25 × 32 × 0.0178 × 1) / 6 = 4.7 V = 2.05% (within 4%)
• Milan water heater: 2,000 W single-phase, 8 m distance, Inom = 9.7 A. Cable 2.5 mm² N07V-K + PVC corrugated conduit CEI 23-46. ΔV = (2 × 8 × 9.7 × 0.0178 × 1) / 2.5 = 1.1 V = 0.48%. C16 MCB + 30 mA RCD
• Cuneo Piedmont mechanical workshop 30 kW three-phase: CNC lathe + presses 50 m. Inom = 54 A. Cable 50 mm² FG7OM1 5G50 buried PE conduit. ΔV = (1.732 × 50 × 54 × 0.0178 × 0.8) / 50 = 1.33 V = 0.33%
• Modena Emilia-Romagna 14 kW air-water heat pump: 230 V single-phase, 12 m outdoor unit-panel. Inom startup 64 A. Cable 16 mm² + C63 MCB + Type A 30 mA RCD

Italian electrical norms

Italian electrical installation norms:

• CEI 64-8 V8 eighth edition 2024 low voltage installations: part 4 safety (chapters 41-44 direct/indirect contact, overcurrent, overvoltage protection), part 5 selection installation, part 6 verifications, part 7 special locations (bathrooms 701, swimming pools 702, medical 710, wind 712). Italian performance levels (CEI 64-8 V4 2003 first introduction): level 1 basic, level 2 standard, level 3 advanced home automation
• CEI 64-50 2024 residential commercial with minimum 8/12/24 DIN modular panel
• CEI 0-21 2024 LV grid distributor connections (ENEL Italy 2018 spin-off Distribuzione SpA, Areti Rome, Unareti Milan, A2A Reti Brescia, Acea Rome 1909)
• CEI EN 60898-1 2019 domestic MCBs (BTicino Varese 1936 Salvavita invented 1971 Carlo Ferrarini, ABB SACE Bergamo 1948, Schneider Electric ex-Cabur Crema 1885, Gewiss Cenate Sotto Bergamo 1970, Vimar Marostica Vicenza 1945)
• CEI EN 61008/61009 RCD/RCBO 30 mA Type AC/A/B/F
• D.Lgs. 81/2008 art. 80-87 electrical risk + D.M. 37/2008 conformity declaration DICO mandatory + DPR 462/2001 grounding periodic verifications: residential 5 years ASL, industrial 2 years high fire risk. Italian tax bonuses: Bonus Casa 50% L. 197/2022; Sismabonus 65-85%; Ecobonus 65% heat pumps; Superbonus 65% 2025 EV chargers + insulation

How the calculator applies the CEI 64-8 standard

The sizing starts from the conductor resistivity (0.0175 Ω·mm²/m for copper, 0.0287 for aluminium), corrected for the operating temperature, and checks in parallel the voltage-drop criterion and the thermal-ampacity criterion. The base ampacities come from the CEI-UNEL 35024/1 table and are corrected with factors for installation method, ambient temperature (per IEC 60364-5-52) and circuit grouping. The chosen section is the smallest commercial one satisfying both constraints with a 10% safety margin, and the breaker is coordinated per the condition Ib ≤ In ≤ Iz. It remains an estimation tool: the executive design of the installation is the responsibility of a qualified professional.

Updated July 2026