Power in balanced three-phase circuits: The formulas for calculating active, reactive, and apparent power in balanced three-phase circuits are the same as those used for single-phase circuits. Based on the formula for power in a single-phase circuit, the active power dissipated in each phase of either a wye- or delta-connected load is equal to:

where P_phase is the active power dissipated in each phase of a three-phase circuit, expressed in watts (W)
I_phase is the phase voltage across each phase of a three-phase circuit, expressed in volts (V)
E_phase is the phase current flowing in each phase of a three-phase circuit, expressed in amperes (A)
φ is the angle between the phase voltage and current in each phase of a three-phase circuit, expressed in degrees (°)

Therefore, the total active power P_T dissipated in a three-phase circuit is equal to: