A poor power factor means paying for current you don’t use productively

Power factor below 1.0 means some current flows just to sustain a magnetic field (in motors, transformers) without doing useful work — utilities often bill industrial customers extra for this "reactive" demand.

Why it works

Real power (kW, the useful part) and apparent power (kVA, what the wiring and generator actually have to supply) diverge as power factor drops — correcting it with capacitors reduces wasted current without changing the useful work being done at all.

Do it exactly

Estimate with the rule, then check it against the calculator that models it properly.

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