AC New Install — Power Wiring (Single-Phase, Three-Phase, Dedicated Breaker)

Step 1 — Verify power type, voltage, ampacity from manual; select materials

Check: Small 9–12k BTU: 115V or 220V single-phase. Medium 18–36k BTU: 220V single-phase. 5-ton+ or VRF: 380V three-phase. Power cable: 14/4 stranded (≥300V rated) — short 14 AWG, long 12–10 AWG. Dedicated breaker: ≥125% of rated current (per NEC).

What to do: Use jacketed cable with KS/UL certification. For three-phase, label phase order (R-S-T) accurately — reverse phase causes compressor reverse rotation (instant damage). Breaker terminal torque: 4–6 N·m (per maker spec). Use crimped lugs — never insert bare conductor.