# Three-phase current: P = √3 × VL × IL

- Source-Date (SAST): 2023-11-08 15:50
- From/To: Eric → support
- Dest: both
- Review-after: 2027-02-28
- Status: current
- Source: company email (Archives/Internal Affairs), 2023-11-08

## Facts

- Three-phase: **P (kW) = √3 × VL × IL**. √3 ≈ 1.732. **VL** (line voltage) is **380 V** in most SA installs. **IL** is current per line.
- Example: 7.5 kW vacuum pump → 7500 = 1.732 × 380 × IL → **IL ≈ 11.4 A**.
- Circuit-breaker minimum: **CNC machines × 1.25**; **motors × 1.5** (so 11.4 A motor → about 17 A minimum).
- Worked load example: 5.5 kW-spindle CNC router with cooler ≈ **8 kW** whole machine, plus **7.5 kW** vacuum pump, plus **3 kW** dust collector — size the breaker from the summed kW using the formula and the CNC/motor factors above.