How this calculator works
Each appliance row contributes quantity times real watts. Dividing by its power factor estimates apparent loading. Apparent loads are added as a conservative inventory estimate; this does not model phase-angle cancellation. A three-phase inventory assumes balanced distribution across phases. The allowance applies a 1.25 multiplier only to the portion marked continuous. It does not select a standard breaker rating or verify conductor ampacity, inrush, interrupting capacity or local code compliance.
Formula
Sum P = sum(qi Pi); Sestimate = sum(qi Pi/PFi); I = Sestimate/V for single phase, or Sestimate/(sqrt(3)VLL) for balanced three phase. Iallowance = I[1+0.25 c]. DC uses PF = 1.
Worked example
One 1200 W DC load at 120 V draws 10 A. Treating all of it as continuous gives a 12.5 A allowance. A balanced 3000 W three-phase load at 100 V and PF 0.8 draws 21.6506 A.
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Frequently asked questions
Does this give an approved breaker size?
No. It calculates a load allowance. A qualified electrical designer must match the breaker, conductors, installation and local rules.
Why no automatic appliance wattages?
Ratings vary greatly. Use the actual appliance nameplate or measured input power rather than a generic appliance label.
When is the 125% factor appropriate?
It is a common continuous-load sizing convention for standard-rated breakers. Requirements and exceptions vary with equipment and jurisdiction; enter the actual continuous fraction.