If you have a local Radio Shack, they have a neat little device called a "kill a watt". it plugs into your outlet and lets you plug a device into it, and gives you voltage, wattage, power factor, amperage ect. I paid right at $20 for mine. you could check at each point where you have lights plugged into an outlet and get a total power. To totally go around my house I have around 1500 watts of lights.