Can we reduce electricity bill in domestic commection by adding PF capacitors, if possible what is the rating?
A small advantage is obtained but it is largely a gimmic. Using PF capacitors definitely results in reducing the current drawn with certain types of loads like motors but does not affect the power directly because power is a result of the product of voltage, current and power factor. The current would have reduced to the extent the pf has increased. A vendor would demonstrate how the current has reduced and so you are saving money on bills. But as I said, that is not entirely correct. A small saving would occur because the lowered current would reduce the power loss in the lines bringing the supply from the meter to your home. This is itself a small figure so a saving in thsi would not significantly reduce your bills. You may not even notice the difference. The capacitor must be rated for AC operation at a voltage exceeding your maximum expected power line voltage by say a 10% margin at least. The value of the capacitor depends on the amount of inductive load.