Cable Size for AC Calculator
Pick your AC tonnage to get the recommended copper cable size and MCB rating for a safe, dedicated air-conditioner circuit.
What cable size for a 1.5 ton AC?
A 1.5 ton split (around 1600 W) runs best on 4 sq mm copper cable with a dedicated 20 A C-curve MCB. For runs longer than 15 m, use 6 sq mm.
How this works
Air conditioners should always run on a dedicated circuit with their own MCB — never through an extension board. A 1.5 ton split typically needs 4 sq mm copper cable and a 20 A MCB; long cable runs are stepped up one size to keep voltage drop within limits.
Why an AC needs a dedicated circuit
An air conditioner is a heavy, motor-driven load that pulls a surge each time the compressor starts. Running it through a shared socket or an extension board overheats the wiring and trips other appliances. Give every AC its own cable straight from the distribution board, its own MCB, and ideally an RCCB for shock protection.
Sizing for the cable run
The tonnage sets the base cable size, but the distance matters too. Beyond about 15 m the voltage drop over a thin cable can make the compressor labour and trip, so the calculator steps the cable up one size for long runs. A C-curve MCB is used because it tolerates the compressor's start-up surge without nuisance tripping.
| AC size | Approx load | Copper cable | MCB |
|---|---|---|---|
| 1 Ton | 1100 W | 2.5 sq mm | 16 A |
| 1.5 Ton | 1600 W | 4 sq mm | 20 A |
| 2 Ton | 2200 W | 4 sq mm | 25 A |
| 2 Ton (long run) | 2200 W | 6 sq mm | 25 A |
Frequently asked questions
What cable size for a 1.5 ton AC?
A 1.5 ton split (around 1600 W) runs best on 4 sq mm copper cable with a dedicated 20 A C-curve MCB. For runs longer than 15 m, use 6 sq mm.
Can I run an AC on a normal 6 A socket?
No. A normal 6 A socket and its 1.5 sq mm wire cannot carry an AC safely. ACs need a dedicated 16-25 A circuit wired directly from the board.
Do I need an RCCB for the AC?
It is strongly recommended. A 30 mA RCCB protects against electric shock and earth leakage, which matters for an outdoor unit exposed to rain.
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