Does StopWatt really work?

What power-factor correction does

Motors and other inductive appliances draw two kinds of current: real current that does work, and reactive current that swings back and forth between the appliance and the grid. Capacitors placed near those loads supply part of the reactive current locally, which reduces the total current flowing through the wiring.

Less current in the wiring means slightly lower resistive (I²R) losses inside your home's circuits and cooler-running conductors. That effect is real and measurable with the right instruments.

Why that may not shrink your bill

Residential meters in the United States generally measure real power in kilowatt-hours. Reactive power is not billed to homeowners the way it is to many commercial and industrial customers, who pay demand or power-factor penalties.

So while StopWatt can improve power factor at the outlet level, the savings that show up on a US home bill come only from those smaller in-home losses — not from the reactive power itself.

Homes most likely to see a difference

• Older houses with long circuit runs and aging wiring.
• Homes running multiple motor loads: pool pumps, well pumps, compressors, window AC units, shop tools.
• Homes where those motors run for many hours a day.

Homes least likely to see a difference

• New, well-wired homes with short circuit runs.
• All-electric heating and cooking loads, which are resistive.
• Homes already dominated by LED lighting and modern inverter appliances with built-in correction.

The test we recommend

Track kWh, not dollars, for one full billing cycle before and after. Compare against the same season a year earlier. If your usage pattern does not move, return the units.

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