A 2-ton AC draws about 9 to 12 amps while running, but its compressor can pull roughly 4 to 6 times that current at startup.
That brief surge, not the running current, usually decides the generator, inverter, or soft starter you need.
Published starting-current figures often disagree because they measure different things: compressor-only inrush, whole-unit startup, or the nameplate’s locked-rotor ceiling.
Typical ranges appear throughout this article, but your unit’s nameplate overrides all of them.
| Measure | Typical 2-ton AC | Where to find it |
| Running current (RLA) | 9 to 12 A at 230 to 240 V | Nameplate |
| Starting current (LRA), fixed-speed | About 45 to 65 A | Nameplate |
| Starting current, inverter | About 14 to 18 A | Spec sheet or clamp meter |
| Generator for a fixed-speed unit | 5 to 7.5 kVA | Calculated below |
What Is Starting Current on a 2 Ton AC?
Starting current is the brief surge a compressor motor draws while its rotor is stationary or just beginning to turn, before it accelerates.
The current settles to its running value. At standstill, the motor has almost no back-EMF opposing the supply, so it draws a much higher current until it reaches speed.
- RLA (rated load amps): the compressor current at its rated running conditions.
- LRA (locked rotor amps): the current the motor would draw with the rotor prevented from turning; it is the worst-case design ceiling printed on the nameplate.
- Inrush current: the actual startup current. Its RMS value is usually below LRA once the motor begins to accelerate, although the first half-cycle can contain an asymmetrical peak above the steady locked-rotor value.
| Term | Meaning | When it occurs | Where to find it |
| RLA | Normal running current | Continuously while cooling | Nameplate |
| LRA | Locked-rotor current | A worst-case ceiling, not normal operation | Nameplate |
| Inrush | Real startup current | First 1 to 3 seconds | Measured with a clamp meter |
The surge is greater after a hot restart because refrigerant pressure has not yet equalized across the compressor.
A compressor that restarts seconds after shutdown may therefore struggle more than one starting from rest.
How Many Amps Does a 2 Ton AC Draw at Startup?
A fixed-speed 2-ton AC commonly has an LRA of about 45 to 65 A on its nameplate.
The measured startup current is often below that ceiling and lasts about 1 to 3 seconds.
An inverter model starts much more gently, commonly around 14 to 18 A, because its drive ramps compressor speed upward.
| AC type | Supply | RLA (A) | Typical start current (A) | Start as multiple of RLA |
| Fixed-speed | 230 to 240 V | 9 to 12 | 45 to 65 (LRA) | 4 to 6x |
| Fixed-speed with soft starter | 230 to 240 V | 9 to 12 | 14 to 25 | 1.5 to 2.5x |
| Inverter | 230 to 240 V | 8 to 9 | 14 to 18 | 1.5 to 2x |
Published sources disagree because they measure different things. This table puts them side by side.
| Claim | What it actually measures | Converted to amps |
| 20 to 40 A compressor inrush | Compressor only | 20 to 40 A |
| 14 to 22 A start, 2 to 3 seconds | Whole unit, labeled “start amps” | 14 to 22 A |
| 3,480 W running, 8,500 W surge | Whole unit, in watts | About 35 A at 240 V |
| 3 to 6 times running amps | LRA-style multiplier, no values given | About 27 to 72 A |
These figures are not necessarily contradictory: one describes compressor-only inrush, one describes whole-unit startup, and another describes the locked-rotor ceiling.
The number that matters for your installation is on the outdoor unit’s nameplate.
Split AC 2 Ton Starting Current
A split AC uses the same compressor types as a window or ducted unit, so its starting current depends on whether the compressor is fixed-speed or inverter, not on the cabinet style.
- The compressor is in the outdoor unit, so the startup surge appears on the outdoor unit’s supply.
- The indoor unit adds only a small fan load.
- Most 2-ton splits use a 220 to 240 V single-phase supply.
- Read the outdoor unit’s nameplate, because the indoor unit’s label does not list the compressor’s LRA.
2 Ton AC Starting Current: Inverter
| Setup | Surge as multiple of RLA | Peak kVA at 230 V (example) | Notes |
| Fixed-speed | 4 to 6x | About 12.7 kVA (55 A) | Highest surge; needs the largest supply |
| Fixed-speed with soft starter | 1.5 to 2.5x | About 4.6 kVA (20 A) | Soft starters can reduce inrush by up to 75% |
| Inverter | 1.5 to 2x | About 3.7 kVA (16 A) | Compressor ramps up instead of spiking |
An inverter drive raises compressor speed gradually, which is why its startup looks like a small bump rather than a spike. See the full breakdown in this inverter vs non inverter AC comparison.
2 Ton AC Amps Single Phase
Most 2 ton ACs run on single-phase power and draw about 10 to 12 amps at 220 to 230 V.
For the same power, current falls as supply voltage rises. For wider context, see these AC electrical power requirements.
| Single-phase supply | Running amps for a 2.2 kW load (power factor 0.9) |
| 208 V | 11.8 A |
| 220 V | 11.1 A |
| 230 V | 10.6 A |
| 240 V | 10.2 A |
Lower supply voltage raises the current required for the same power, which is why a weak supply makes both running and starting problems worse.
Three-phase versions of 2 ton units exist, but they are uncommon in homes.
2 Ton AC Amps Calculator
You can calculate the supply a 2-ton AC needs from two nameplate numbers, RLA and LRA, using one formula and three steps.
kVA = amps x volts / 1000
- Find RLA and LRA on the outdoor unit’s nameplate.
- Multiply each by your supply voltage and divide by 1,000 to get running kVA and starting kVA.
- Choose a generator whose surge rating covers the starting kVA, or whose rated output covers the soft-started or inverter surge.
Worked example, using illustrative values of RLA 10 A, LRA 55 A, and a 230 V supply:
- Running load: 10 \times 230 / 1000 = 2.3 kVA.
- Starting load: 55 \times 230 / 1000 = 12.65 kVA, for one to three seconds.
- A fixed-speed unit may therefore need a generator with a surge rating around 5 to 7.5 kVA, depending on the generator’s short-term overload capability.
- With a soft starter reducing startup to about 20 A, or 4.6 kVA, a 3.5 to 4 kVA generator is a more realistic target.
- An inverter unit starting near 16 A, or 3.7 kVA, commonly works on a 3 to 3.5 kVA generator.
Do not assume every generator can supply 2 to 3 times its rated kVA. Check the manufacturer’s surge or peak rating, because it varies by model and duration.
| Your nameplate | RLA (A) | LRA (A) | Voltage (V) | Running kVA | Starting kVA |
| Enter your values |
The nameplate LRA is a ceiling, so the only way to know what your unit actually draws is to measure it.
- Set a clamp meter to its inrush or peak-hold (min/max) mode.
- Clamp one live conductor, never the whole cable, at the outdoor unit’s isolator.
- Let the compressor remain off for at least three minutes so it starts from rest.
- Start the unit and record the peak reading.
- Repeat three times and use the highest reading.
- Measure supply voltage before and after startup to see how far it dips.
If the AC runs normally at steady load but fails at startup, the cause is often voltage sag rather than insufficient total capacity. Common signs include:
- Lights dim briefly as the compressor starts, indicating voltage drop under the surge.
- The compressor hums but does not start, indicating the voltage fell too far for the motor to turn.
- The generator bogs down or its output breaker trips, indicating the surge exceeded its short-term rating.
- The breaker trips at the instant of startup rather than later, which may point to an undersized or weak supply, an incorrect breaker, or a failing capacitor.
Run your own numbers through this generator size calculator to confirm the result.
2 Ton AC Inverter AC Ampere Load
A 2-ton inverter AC typically draws about 8 to 9 amps at steady running load, lower than a fixed-speed unit because its compressor adjusts speed to the room instead of cycling on and off.
| Inverter model | Running amps | Start amps |
| 5-star inverter | 7.8 to 8.5 A | 14 to 17 A |
| 3-star inverter | 8.5 to 9.1 A | 15 to 18 A |
2 Ton AC Load in KW
A 2-ton AC typically has an electrical load of about 1.8 to 2.6 kW. This is the power it consumes, not the 24,000 BTU per hour of cooling it delivers.
| Unit type | Running kW | Running watts | kVA at 0.9 power factor |
| Inverter, 5-star | 1.8 to 1.95 | 1,800 to 1,950 | 2.0 to 2.2 |
| Inverter, 3-star | 1.95 to 2.1 | 1,950 to 2,100 | 2.2 to 2.3 |
| Fixed-speed, 5-star | 2.0 to 2.2 | 2,000 to 2,200 | 2.2 to 2.4 |
| Fixed-speed, 3-star | 2.1 to 2.35 | 2,100 to 2,350 | 2.3 to 2.6 |
| US central unit, 240 V | 2.2 to 3.8 | 2,200 to 3,800 | 9 to 16 A x 240 V |
A Ton AC Socket Amp
A 2-ton AC needs a dedicated circuit and a socket or fixed connection rated for the actual nameplate load.
In practice, inverter models commonly use a 20 A heavy-duty socket, while some fixed-speed models need a 25 A or 32 A circuit and fixed isolator rather than a conventional socket.
| AC type | Typical MCB | Minimum socket or connection rating |
| Inverter | 20 A | 20 A heavy-duty socket |
| Fixed-speed, 3 to 5-star | 25 A | 25 A connection or fixed isolator |
| Fixed-speed, 2-star or high-load | 32 A | 32 A connection or fixed isolator |
- Use a metal-clad socket box where a plug-and-socket connection is used, because plastic fittings can soften if a plug runs warm.
- Do not use an ordinary 16 A socket for a fixed-speed 2 ton unit unless the manufacturer’s installation instructions specifically allow it.
- Never use an extension cord or power strip; the connector becomes the weak point in the circuit.
- A hard-wired connection through a fixed isolator is the safest option for a permanent unit.
How Much Ampere Switch Is Required for a 2 Ton AC?
A 2-ton AC typically needs a 20 A C-curve MCB for an inverter unit and a 25 A C-curve MCB for a fixed-speed unit.
Size the breaker from the nameplate’s maximum overcurrent or recommended branch-circuit protection, not from the starting surge alone.
| AC type | Typical MCB | Curve |
| Inverter | 20 A | C |
| Fixed-speed | 25 A | C |
| Older or higher-load fixed-speed | 32 A | C |
A C-curve MCB tolerates a brief magnetic trip threshold of about 5 to 10 times its rated current, which is why it can usually ride through a compressor startup.
A breaker that trips at startup may be undersized, incorrectly rated, supplied by a weak circuit, or protecting a failing compressor capacitor.
Check your AC breaker size chart against the nameplate before choosing.
2 Ton AC Wire Size in mm
A 2-ton AC typically needs 4 mm² copper wire. A 2.5 mm² copper conductor may be acceptable only for a short run protected by a 20 A or smaller breaker, because voltage drop over distance matters as much as heat.
| Copper size | Approx. current rating | Max MCB | Max run at 10 A for 3% voltage drop (230 V) |
| 2.5 mm² | About 20 to 27 A | 20 A | About 38 m |
| 4 mm² | About 28 to 37 A | 25 to 32 A | About 62 m |
| 6 mm² | About 36 to 46 A | 32 to 40 A | About 94 m |
These values assume PVC-insulated copper and vary with installation method, grouping, and ambient temperature.
Confirm the final selection against your local code, such as IEC 60364, BS 7671, or the NEC.
The run lengths use typical voltage-drop factors of about 18, 11, and 7.3 mV per amp per metre for 2.5 mm², 4 mm², and 6 mm² copper, respectively. Match your result to the AC wire size chart.
Can a 2 Ton AC Run on 2.5mm Wire?
A 2-ton AC can run on 2.5 mm² copper wire only for a short run, typically about 30 metres or less, on a 20 A or smaller MCB.
Use 4 mm² copper if the circuit uses a 25 A breaker, runs farther, or is installed in a hot or heavily enclosed location.
Based on our AC installation and maintenance service, if you use a 2.5 mm² wire, it “will overheat,” but the practical limit is not the brief startup surge.
The wire carries only about 10 to 12 A while running, which is within its current-carrying capacity under favourable installation conditions.
The more important limits are the protective device rating, installation method, ambient temperature, and voltage drop on a long run.
Check these in order:
- Measure the cable length from the distribution board to the outdoor unit.
- Confirm the MCB rating, because 2.5 mm² should not normally sit behind more than a 20 A breaker.
- Check whether the cable runs in conduit, trunking, insulation, or is grouped with other cables, all of which can lower its current rating.
- Consider ambient heat, because a cable in a hot roof space carries less current safely.
- Confirm the conductor is copper, because aluminium needs a larger size for the same load.
If any check fails, step up to 4 mm².
Size your supply before you buy: run your nameplate numbers through our generator size calculator and pick the wire from our comprehensive AC wire size chart.