Pick your country and the appliance. You get the current it draws, the circuit breaker it needs, and whether it can plug in or must be hard-wired.
Typical ratings for large appliances in your country. Tap a row to load it into the calculator. Always check the rating plate on the actual model.
| Appliance | Typical power | Voltage | Current | Breaker |
|---|
Single-phase current is power divided by voltage: I = P ÷ (V × PF). On three-phase it's I = P ÷ (√3 × V × PF), using the line-to-line voltage.
The breaker is the smallest standard size at or above the design current. Loads that run for 3 hours or more get a 125% allowance, which the NEC requires in North America and is good practice everywhere.
Check the rating plate or spec sheet for the input power, then check your switchboard has a spare way and enough supply capacity. Large appliances often need a new circuit.
Divide the power in watts by the supply voltage. A 2400 W heater on 230 V draws 2400 ÷ 230 = 10.4 A. On 120 V the same heater would draw 20 A.
At 230 V a 3.6 kW element draws about 15.7 A. Because a storage tank heats for hours, a 20 A breaker on 2.5 mm² cable is the usual choice in Australia and New Zealand.
In Australia and New Zealand, yes. Appliances are rated at 240 V, so 2400 W is 10 A, which suits a standard 10 A power point. Avoid running it from a power board or extension lead.
Use the electrical input power. A 7 kW split system typically draws around 2 to 2.5 kW of electricity. If the installation manual gives a breaker size, use that.
Loads that run for three hours or more, such as hot water, heaters and EV chargers, are sized at 125% of their current. Breakers in an enclosed switchboard run warm, and this allowance stops nuisance tripping.