What is the formula to figure out how much running an electronic device will effect my electric bill?

Question

I want to be able to look at my window unit A/C and figure out what it costs me per day, per hour, per month.... whatever.

Help!!!

Answer 1

All of your electrical items will have the voltage frequency and load ratings marked on them someplace. The information may be on a nice label that is easy to find and read, or it might be molded into the plastic or stamped someplace. Items in your home will be either 120 volts or 240 volts or something close to those figures like 110V, 115V, 208V or 220V. The frequency will be 60 Hz for the USA, Canada and a few other places and 50 Hz for most other parts of the world. The load may be marked as amperes, abbreviated amps or “A.” The load could be marked as watts, wattage or “W.” The wattage might be marked instead of the amperes or in addition to the amperes. There could be other markings such as “1 phase.” If phase is marked, it will always be 1 phase or 1 ph for home items. Industrial equipment is often 3 phase. Some items may list parts separately such as the motor and heater in an electric dryer.

Your electric bill should have something on it to indicate your total energy usage for the month. The total usage should be stated in kilowatt hours or kWh. The price per kWh should be stated as something like $0.0945 / kWh. There may also be some other charges. There may be some fixed charges and some surcharges or fuel cost adjustments stated per kWh. To find your cost per kWh you could add up the charges stated per kWh or divide the total bill amount by the total usage.

To find how much it costs to operate an electric device, multiply the watts marked on the device by the total number of hours that it is turned on during the month or any time period of interest and divide by 1000. That is you kilowatt hours of usage for that item. Multiply the kWh by your cost per kWh to find the cost of operation.

If the watt rating is not marked, multiply the amp rating by the volt rating. That will give you a watt rating that may be a little more than the actual watts used for some motorized items, but it should give you a reasonable estimate.

It will be difficult to estimate the usage time for things that turn on and off by themselves such as an air conditioner, water heater or refrigerator. In the USA, you can buy a monitor that plugs in between an appliance and an outlet. It can add up the kilowatt hours of usage for a period of time. Look at:
http://the-gadgeteer.com/review/kill_a_watt_electric_usage_monitor_review

Answer 2

You will need to find the wattage ratting for this device. If it is not on it or the net, you will need to figure it out yourself. Since you are asking this, I think it is better if I don’t tell you the correct way to do it because it is in depth and dangerous; however, you could turn everything off in your house and go out side to your meter. Count the power it is using in one minute times 60 minutes (the new number will be your pre hour usage). Then do the same with the air on. Subtract them. And this is about what it is per hour of run time. Keep in mind that it uses a little extra power to start and it stops when the temp reaches where you set it. After you have the watts or kilowatts, compare this to the cost per unit on you electric bill.

Answer 3

There probably is a formula, however energy prices are not a constant, so you would have to consider the variable cost of electricity. Most appliances have that yellow tag on them that gives you a ballpark figure of the annual cost of electricity to run that particular appliance.