# Determining Electrical Usage of a Device

Discussion in 'General Electronics Discussion' started by RhinoCan, May 2, 2011.

1. ### RhinoCan

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May 1, 2011
I am not an electronics hobbyist, just a guy who uses electronics regularly to do useful things.

In the spirit of reducing electrical consumption, I have some very basic questions that I hope someone here can answer.

1. If I have a device, say a printer or stereo component, plugged into an electrical outlet - I'm in Canada where we have 110 Volt AC - does it consume electricity if it is not actually turned on? For example, my printer is always plugged in but the on/off LED is usually not lit. Am I safe in assuming that it is not using electricity when the LED is off and only consumes electricity when the LED is actually shining? The reason I'm a little confused on this point is that one of my stereo components has an LED in the power switch and that LED is lit when the unit is powered off so it would be appear to be getting SOME electricity, hopefully just enough to light the LED! (Naturally, the stereo has a lot more lights and displays on when it is actually powered on.)

2. How can I determine exactly how much electricity a specific device is consuming? For instance, suppose I wanted to know how many kilowatt/hours it took to charge a couple of rechargeable batteries for 16 hours? Or how much electricity it consumed to keep that LED on my stereo lit? Is there some kind of affordable gadget out there that I could plug into the circuit to measure just how much electricity the device uses in a given period of time? I'm picturing something that the device's plug goes into, then the electricity-consumption-measuring gadget would get plugged into the wall outlet. The gadget would probably feature a digital display that you would reset to zero before each use and then count up how many kilowatts it had consumed until you disconnected it. If such a gadget exists, what is is called? I just want to be sure such a beast exists and what it is called, then I can try to track one down locally and see how much power each of my devices actually uses.

2. ### davennModerator

13,903
1,971
Sep 5, 2009
there are plug in watt/hour meters available these days
they plug into your wall outlet and then your appliance piggyback plugs into it. Some are able to give a contineous power usage reading and also store usage data, others just give a contineous usage reading.

do some google searching will probably bring up some examples, over here a local electronics store sells them for ~ the \$30.

Dave

here we go from your region of the world ... Home Depot...

http://www.homedepot.com/webapp/wcs...1&cj=true&srccode=cii_9324560&locStoreNum=121

Last edited: May 2, 2011
3. ### RhinoCan

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May 1, 2011
Thank you VERY much for this information, Dave! I'd heard that such devices existed but I wasn't sure if they actually did what I wanted them to do or what they were called, let alone where to buy one. We have a couple of Home Depots in town here so getting one of these gadgets should be no problem. Using it will also help me answer the first of my two questions quite definitively!