Discussion in 'Homework Help' started by Bush600, Mar 21, 2013.

  1. Bush600

    Thread Starter New Member

    Mar 21, 2013
    Can anyone out there confirm or deny that adding a 1.2KVAR capacitor to a single phase 120/240V residential panel will reduce total kwh usage and reduce power company bills?
    Last edited: Mar 21, 2013
  2. antonv

    Active Member

    Nov 27, 2012
    I don't have experience with this but since no one else has answered I will say what I think: you cannot tell if it will or won't save you anything unless you know whether your house as a whole presents an inductive load or not. And it might change depending on whether you do laundry (run motor loads) or not.

    So my guess is, it depends.
  3. WBahn


    Mar 31, 2012
    Depending on where you live, your meter is most likely real power responding meaning that it only measures your real power usage. So dinking with your power factor won't save you a dime, though if there is any leakage in the cap you will get to pay extra for that.

    Let's assume that you actually have an apparent power responding meter.

    Consider the question phrased a slightly different way, "I have no idea what my power factor is. Will hanging a capacitor on my lines correct it?"

    How can you correct something you don't know?

    With the kinds of loads on residential lines you see today, there is no guarantee that you even have an inductive power factor to start with. If you don't, or if it is small, then hanging a capacitor on their might well move you into a capacitor power factor that is lower in magnitude that what you started with and hence cost you money.

    Ideally what you want to do is measure your actual power factor in real time and then switch in capacitors (and possibly inductors) to correct it for what it is now. Such systems exist and they almost always cost far more than what any potential savings woiuld bring.

    Again, most residential panels use a real power responding meter so they won't save you any money unless enough people do it so as to allow the utility company to lower the rates to reflect the efficiency gains.