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AC Ampere & Breaker Size Calculator

A 1.5 ton 5-star split AC draws about 4.5 A on a 230 V Indian supply; a 3-ton US condenser draws roughly 13 A at 240 V. Use this to pick the MCB / breaker and confirm you need a dedicated circuit.

Inputs

Running current shown; compressor inrush is 3–6× for non-inverter units, which the breaker curve must tolerate. Wiring decisions belong to a licensed electrician.

Reading the numbers like an electrician

The amps shown are running current at the selected efficiency — a 5★ inverter draws ~35% less than a 3★ unit of the same tonnage, so efficiency affects your wiring, not just your bill. Breakers are sized at ≥125% of running current; non-inverter compressors also pull a 3–6× inrush at start-up that the breaker’s trip curve absorbs (inverters soft-start and sidestep it).

Three things this tool leaves to a professional:

  • Wire gauge — length-dependent; our sister voltage-drop calculator covers the panel-to-condenser run.
  • Shared circuits — don’t. An AC gets a dedicated circuit, full stop.
  • Whole-panel capacity — use the panel selector below and the panel capacity guide.
Result
AMPS
Power draw
Suggested MCB / breaker
CircuitDedicated circuit required
Cross-check long cable runs with our sister tool voltdropcalc.com to keep voltage drop under 3%.

Breaker & circuit quick guide

Typical running current and breaker sizes — always confirm against the nameplate MCA / MOCP:

SystemApprox running currentTypical breaker
1 ton split (230 V)~4.5–5 A16 A MCB
1.5 ton split (230 V)~6.5–7 A16–20 A MCB
2 ton split (230 V)~8–9 A20 A MCB
2–3 ton condenser (240 V, US)~10–15 A20–30 A double-pole
4–5 ton condenser (240 V, US)~18–28 A35–45 A double-pole

Figures are indicative; the data-plate MCA (minimum circuit ampacity) and MOCP (maximum overcurrent protection) are the authoritative sizing numbers.

US vs India wiring differences

  • US: central condensers run on 240 V double-pole breakers with a disconnect at the unit; sizing follows NEC Article 440 and the nameplate MOCP.
  • India: splits run on 230 V single-phase with a dedicated MCB; higher total tonnage may need a three-phase connection or a sanctioned-load increase.

FAQ

What size breaker or MCB does my AC need?

Size it to running current plus startup inrush, but let the nameplate have the final word: use the unit's MCA (minimum circuit ampacity) and MOCP (max overcurrent protection). As a rough guide a 1.5-ton split runs on a 16–20 A MCB, and a 3-ton US condenser on a 20–30 A double-pole breaker. A licensed electrician confirms.

Does an AC need its own dedicated circuit?

Yes. Central ACs and most splits need a dedicated circuit — sharing it with lights or sockets causes nuisance trips and is a code problem. Portable and small window units on 15–20 A general circuits are the usual exception, one unit per circuit.

Why is startup current so much higher than running current?

A non-inverter compressor draws 3–6× its running current for a fraction of a second at start (locked-rotor amps). Breakers use a time-delay curve to ride through it. Inverter units ramp up softly and avoid the spike, which is easier on both the breaker and your lights.

Can my 100 A panel take a new AC?

Usually yes for one system — a 3-ton adds roughly 15–20 A — but it depends on everything else already on the panel. The calculator flags likely panel headroom; an electrician's load calculation is the real check before adding a large condenser or a second system.

Method & standards

breaker and circuit guidance follows NFPA 70 (NEC) Article 440 and IS 732; always confirm the nameplate MCA/MOCP — NFPA. See the wiring guide. See our full methodology.