Everyone wants to reduce their electricity bill, but it's a difficult thing to do if you don't know how much electricity your appliances are using. Determining this can be complicated because some appliances, such as refrigerators, turn themselves on and off in an unpredictable way. It's still possible to check or measure the amperage on a refrigerator.
Things You'll Need
- Watt-hour meter
Check the labels. Many refrigerators have a label on the inside end of the door that lists the voltage needed and the amps it uses to run its various components. Some even list the wattage of the device. Also, most electric motors have labels on them that list volts and amps.
To check the label on the refrigerator's compressor motor, push the refrigerator away from the wall and use a flashlight to peer into the backside of your refrigerator. If you can't see the label, don't remove any parts to gain access to it; there are much easier ways to check the amperage of your refrigerator.
Unplug the refrigerator and plug in the watt-hour meter. The watt-hour meter is an electronic device about as big as your hand and can be purchased at most big box stores. It plugs directly into a wall outlet and has an outlet on the other side of it for accepting a plug from a device. Plug the watt-hour meter into the outlet where you normally plug in your refrigerator, then, plug the refrigerator into the watt-hour meter. It has a digital display on the front that shows the current watts.
The watt-hour meter can be read as you're looking at it to find out what the current wattage is, or it can be programmed to capture watt usage over a period of time and then averaged.
Calculate amperage. According to Ohms law, Voltage * Amperage = Watts, so using algebra, Amperage = Watts/Voltage. In this case, we know the voltage is 120, because that's what it is for all homes in the United States. Complete the calculation by dividing the number of watts (read off the watt-hour meter) by the voltage (120).
As an example, say your refrigerator uses 400 watts on average over the course of a 24 hour day. Dividing 400/120 = 3.34 amps. This means your refrigerator uses 3.34 amps of electricity on average during any given day. This number will vary of course, depending on how warm it is in your house. If it's warm inside your kitchen, for example, say on Thanksgiving Day when you're using your oven all day, it's very likely that your refrigerator would use considerably more electricity to keep the temperature steady inside.
Tips & Warnings
- When checking the amperage on a refrigerator, always test over time as the amperage being used depends on whether the compressor and fans are running or not.
- Use your watt-hour meter to test the voltage coming from your wall outlet to make sure it's 120; sometimes it isn't, and that can cause damage to your appliances.
- The watt-hour meter can be left plugged in for an entire month so you can see how much electricity your refrigerator actually used and then calculate how much it costs, since most utility companies charge by the kilowatt hour (kWh).
- Never touch a running electrical motor; it can injure or kill you.
- When testing for amperage on a refrigerator, be sure to plug in the meter first, then the appliance, to prevent surges.
- Bluejay (Mr. Electricity): How do I measure the amount of electricity something uses?
- "Survey of Instrumentation and Measurement"; Stephen A. Dyer; 2001
- Photo Credit rÃ©frigÃ©rateur image by dead_account from Fotolia.com
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