Residential PF Caps -- are they for real?

I've seen several questions on these "residential capacitors" that claim to save 20% of your power bill. Are they for real or are they a SCAM? Any power engineers that can answer this?

A search of the internet came up with only 2 small companies. They do not talk about measuring the PF, and connect to one phase only.


Most USA residences are wired for 240 split phase. I happen to be wired with 2 phases of 120V 3 phase -- 30 condo building that has 3 phase 800A service.

5 Answers

  • 1 decade ago
    Best Answer

    The typical residential home in the US has a peak load power factor in the range of 0.90 to 0.95 lagging. The only way adding capacitors is going to save you on your electric bill is if your electric utility bills you in kVAh instead of kWh.

    Most electric utilities in the US still bill residential customers in kWh, so there is little to be gained by adding capacitors. The ampere reduction is small and the savings from reduced line losses are minimal.

    Side note: An incandescent lightbulb has a near unity power factor. Compact Fluorescent Lighbulbs (CFL) are closer to 0.50 lagging. Desktop computers also have power factors worse than 0.60 lagging.

  • 1 decade ago

    They are single phase only as very very few residents will be served with anything other than single-phase service. While there are some residential usages that will operate at a PF less than 1.00, e.g., HVAC equipment, the fridge compressor, a washing machine, PC's and electronic entertainment items, correcting the household PF will only save energy by reducing the current and therefor the watts lost in the wiring between the meter and the PF connection node. In the USA, almost no residents are metered for PF, so that is not a consideration. Very difficult to believe that there is anyway that anything close to a 20% savings could be had-maybe 2-3% at most. But, would be interesting to see any back-up for such a claim! Probably a scam.

  • Anonymous
    1 decade ago

    While it is true that PFC can save energy it is mainly for big industry who have equipment that pull the power factor away from 1. Home users won't have the big machines that will make much of a difference to the power factor so it is probably a waste of time.

  • yes it can save the power bill. for example, here in austria, we make use of it , and it more reliable than anyother power supply, but it depense on the number of houses and mostly it´s for industrial cities. so, i don´t think, it can be good for a small resident, because some of it have PF of 340V.

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  • 1 decade ago

    yes they can save energy in industries where higher power factor tending to1 are used and also for having all-day efficiency.

    but , when it comes to residents that much higher power factor is not quite supported.

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