How can I measure the electricity a home appliance is consuming?

I'd like to be able to figure out how much it's costing me to use my ancient refrigerator, or my new, 2800W toaster. Maybe to see if it's worth my while to put the laundry on the line outside, or just throw it in the dryer. To measure the amperage, you need to get a reading on just one lead into the plug. Measuring the current in the cable to any appliance yields a net zero amps, because you get the inflow and outflow in the same measurement, and these cancel each other.|||P3 International makes an inexpensive device known as a "Kill-a-watt" that allows the user to measure the volts, amps, watts, volt-amps, power factor, and kilowatt-hours of anything plugged into it. Follow the link below.





Keep in mind that electricty consumption is measured in kilowatt-hours. This is a combination of watts and time. Your refrigerator is running the entire month, yet the toaster is used for brief periods each day.





2800 watts looks a bit high for a toaster. Is this a commercial grade appliance?|||The easiest way is to turn off everything in the house except the thing you want to measure for exactly one hour and check on your consumption meter how many kilowatt hours it uses in one hour.


This is the most accurate way of measuring the consumption as you have a watt meter there ready for your use.





You are obviously not familiar with electricity so i would not suggest you play about with it, it is nasty stuff and can bite.





The current flow is not zero as [to be very simplistic] the current goes in one wire and out the other wire so it is flowing through the appliance.|||ahem..the power useage on the toaster is 2800 watts, or 2.8kw if you prefer. you are charged for useage (kWh), if you run your toaster for 10 minutes, you have used 2.8kW*(1/6hour) = .467kWh





electricity is measured in watts (volts x amps), with capacity or useage over time measured in watt-hours (or kilowatt-hours) you can buy plug in meters that go between the appliance and the outlet, but as long as you know the voltage, you can use a clamp over ammeter to get the amperage (it just clamps over the cord)|||You need a watt meter. I read of one recently for $29.95 Product description is:





"Are your utility bills going through the roof? Track energy consumption with the Kill A Watt Usage Monitor. An LCD readout displays energy consumption by the Kilowatt-hour with a 0.2 percent accuracy rate and monitors voltage, line frequency and power factor. You'll save on electricity once you have identified and replaced or changed your usage of "energy-guzzling" devices. Helps to track and budget electrical expenses by the hour, day, week, month, even an entire year. "





2800 W?? Do you have a 240 V toaster?|||see what the kilowatt hours are on the appliance, its supposed to be on it.|||an amp meter.|||Apparently you have a clamp on ammeter. I'd take a short 3 wire extension cord, #12 wire, and take a knife and carefully separate out the hot wire, without cutting the insulation on each wire. Now you can plug an appliance into it and clamp the ammeter onto the hot lead. Be very careful. Best is the type of cord that's flat, and you can actually see the divisions between the sections.





But only if you have to.





You already have the number for the toaster. 2800x/120v = 23 amps. This seems about 2 or 3 times as high as it should be.





For the refrigerator, remember it will cycle on and off (you can hear it). You can measure the current when it is on, (or read it off the plate on back) but how much power is actually used depends on the duty cycle, ie, on what percentage of the time it is actually running. And that depends on how recently you opened the door, and how recently you put something into it.





A dryer is more difficult, as it has a special plug for 230 volts, 4 wires. Best if you can look it up or calculate it.