Lesson 3.1 — Voltage, Current, Resistance & Power
Cambodia's grid delivers 230 V, 50 Hz single-phase to homes. Ohm's law (V = I × R) and the power law (P = V × I) size every part of your installation: a 2,000 W air conditioner at 230 V draws about 8.7 A, so it needs its own 20 A circuit on 2.5 mm² cable — not a shared lighting circuit. Learn to move between watts, volts and amps without a calculator; it is the mental arithmetic of the trade.
Key points
- V = I × R · P = V × I · I = P ÷ V
- 230 V grid: 1,000 W ≈ 4.3 A as a quick rule
- Cable size follows the current, breaker follows the cable