Frequently Asked Questions

It depends entirely on voltage. At 120V: 1 kW = 8.33 amps. At 240V: 1 kW = 4.17 amps. At 480V three-phase: 1 kW = 1.2 amps per phase (assuming power factor 1.0). There's no single answer without knowing the voltage.

No. Power (kilowatts) and current (amps) measure different things. It's like asking "how many pounds is 50 miles?" You need voltage to connect them. Think of it this way: the same 1 kW heater draws different amounts of current depending on whether you plug it into 120V or 240V.

kW is real power—the actual work being done. kVA is apparent power—the total current flowing times voltage. They're equal when power factor is 1.0 (purely resistive loads). For motors and other inductive loads, kVA is higher than kW. A motor might be rated 10 kW output but draw 11.8 kVA from the electrical supply because of its 0.85 power factor.

Heaters are purely resistive—all the current goes into producing heat. Motors are inductive—they create magnetic fields, which cause current and voltage to be out of phase. This phase difference means some current doesn't contribute to useful work. It's like pushing a shopping cart at an angle instead of straight ahead—you're working harder for the same result.

A continuous load runs for three hours or more at a time. The National Electrical Code requires circuit breakers and wiring to be sized at 125% of continuous loads to prevent overheating. A 30-amp continuous load needs a 40-amp breaker minimum (30 × 1.25 = 37.5, round up to next standard size).

Yes, but aluminum requires larger wire sizes for the same current capacity. Also, aluminum expands and contracts more with temperature changes, which can cause loose connections over time. Most residential installations use copper. Industrial facilities sometimes use aluminum for large feeders where the cost savings outweigh the disadvantages.

Voltage drop reduces the actual voltage at the load. If you calculate based on 240V supply but voltage drop reduces it to 230V at the equipment, the current will be higher than calculated (remember I = P ÷ V, so lower V means higher I). For long wire runs, calculate the voltage drop and use the actual voltage at the load for sizing.

kW (kilowatt) is a measure of instantaneous power — the rate of energy use right now. kWh (kilowatt-hour) is energy — the total amount consumed over time. A 2 kW heater running for 3 hours uses 6 kWh of energy. For the kW to amps calculation, you always use kW (power), never kWh (energy).