Single-phase power is calculated by multiplying the voltage, current, and power factor: P = V × I × PF.

Formula for Single-Phase Power

The real power (P) in a single-phase AC system is determined using the formula: P (Watts) = V (Volts) × I (Amperes) × PF (Power Factor) Where:

• V is the RMS voltage supplied to the distribution box
• I is the RMS current drawn by the load
• PF is the power factor, representing the efficiency of power usage (ranges from 0 to 1) If you want the power in kilowatts (kW), divide the result by 1000: P (kW) = (V × I × PF) / 1000

Example Calculation

Suppose a distribution box supplies 230 V, the current drawn is 15 A, and the power factor is 0.85. The single-phase power is: P = 230 × 15 × 0.85 = 2932.5 W ≈ 2.93 kW This represents the real power consumed by the connected loads in the distribution box .

Notes on Measurement

• Ensure that the voltage and current are RMS values.
• The power factor accounts for phase differences between voltage and current; purely resistive loads have PF = 1, while inductive or capacitive loads have PF < 1.
• This calculation gives active power, which is the portion of electrical power converted into useful work like lighting, heating, or mechanical motion.

Practical Use

• This formula is commonly used for load estimation, energy monitoring, and electrical design.
• For safety and efficiency, always consider the maximum current rating of the distribution box and the power factor of connected devices when sizing circuits . By applying this method, you can accurately determine the single-phase power of any distribution box in residential or light commercial installations.