This might be subjective, I don't know. However, it's a serious problem for me. My electrical bill is outrageous. It's three times as large as my next-door neighbor, and four or five times the size of my neighbor's across the street. It's worse in the summer (I live in central TX), but I've had the air conditioner inspected, and while the house is right at the maximum capacity for our unit, the unit should still be able to take care of the load. That also doesn't explain why our winter bills are larger than the comparables.

What I would like to do is check the amount of current drawn by each running appliance and calculate where all my money is going. I just don't know how to go about doing this.

  • 9
    Don't forget you need to take into account the duty cycle of each appliance as well. For example, your heat pump may draw exactly the amount of current it's supposed to, but if it's running constantly instead of for 15 minutes per hour, that's 4X the energy usage. Commented Oct 26, 2010 at 14:42
  • Have you verified the meter readings? Do the numbers on the bill match up with those on the meter?
    – mohlsen
    Commented Oct 26, 2010 at 15:04
  • Do you run the AC all summer long, and the heat all winter? What temperature do you set the thermostat to, and how does that compare to your neighbors?
    – Jay Bazuzi
    Commented Nov 19, 2010 at 14:04

8 Answers 8


For devices that plug into an electrical outlet, you can use Kill-a-Watt or equivalent to monitor how much electricity they're using.

If that doesn't give you a clear culprit, one low-tech method is to look at the electric meter as you turn off circuits at the service panel one at a time until you see a big change in speed at which the wheel is spinning (for older meters) or the digits are changing (newer meters). If you can narrow down what's using a lot of electricity, you can look at devices one at a time on that circuit to see if one is using more than its fair share.

  • Does the Kill-a-Watt work on 240 lines, say for stoves and dryers?
    – Tester101
    Commented Oct 26, 2010 at 11:57
  • @tester101: No, it's for 120V lines only.
    – Niall C.
    Commented Oct 26, 2010 at 13:59
  • So it's not good for the real energy hogs?
    – Tester101
    Commented Oct 26, 2010 at 14:06
  • 2
    @tester101: No, but it's great for finding things that are worthwhile to unplug because they're using a lot of electricity when they're off, for some value of off. Big appliances aren't so easy to unplug since you often have to move them to get at the plug.
    – Niall C.
    Commented Oct 26, 2010 at 14:11
  • 1
    I guess my problem with this solution is that you are only going to find the small energy vampires, which I'm not convinced will save that much money. I bought a surge protector that can be completely shut down for my entertainment center, and have yet to see any significant savings in my electric bill.
    – Tester101
    Commented Oct 26, 2010 at 14:30

You could invest in a clamp on Ammeter like this

alt text

Then open up your electrical panel and measure the draw on each circuit, this will show you which circuits are drawing the most.

Also as Mike Powell pointed out, you could clamp on to the main lines and then turn off each breaker noting how much the value drops. (You will have to do this for each leg of the main).

Once you know which circuits are drawing the most power, you can start eliminating devices on that circuit until you find the largest consumers.

If you want you can figure out how much your devices cost to run like this.

 Watts = Amps * Volts
 Kilowatts = Watts/1000
 Kilowatt-hours = kilowatts * Hours used
 Cost = kilowatt-hours * cost per kilowatt-hour


 Cost = (((Amps * Volts)/1000) * Hours Used) * Cost per Kilowatt

You could also do like I did and split an old extension cord (so you can clamp on to a single wire), then plug one end into the wall, and your device into the other end. Then you can measure the draw of just that device.

  • 4
    If your panel is fairly packed with wires (like mine), you might find it easier to clamp a device like this on one of the mains coming in, and then note how much the current decreases as you switch each breaker off temporarily, instead of trying to get the clamp around each of your branch circuit wires. Commented Oct 26, 2010 at 14:37
  • I've got one of those, VERY handy. Even came with a inline splitter so you can use it on individual accessories just like one of those kill-a-watt devices. Commented Oct 27, 2010 at 14:58
  • Stupid "submit on enter" bug bit me again... Anyways, continuing on my comment... If you ever think you might want to do the same on your car (or other DC devices) spend the extra few $ and get a Hall effect meter. The cheapies only work on AC. Hall effect (type, not a brand) works on AC & DC. Commented Oct 27, 2010 at 14:59
  • @MikePowell Klein Tools now offers a Hook Meter That works great in cramped panels (though it is a bit expensive for a DIYer). Here's a Demo Video.
    – Tester101
    Commented Apr 6, 2012 at 20:20

Turn off and unplug everything and I do mean everything.

If the meter is still showing that you are using electricity the you have a fault with the meter and you should report it to your utility company.

  • 2
    Could you just flip the main breaker from the house?
    – Joe
    Commented Sep 11, 2010 at 12:44
  • 2
    @Joe - That should work too - as long as the breaker is the house side of the meter. I wasn't sure about how things are organised in the states.
    – ChrisF
    Commented Sep 11, 2010 at 13:37
  • I will try that. It may provide a quick answer that will alleviate the need for me to unplug everything in my house, replug it back into a kill-a-watt, and then unplug and replug again.
    – moswald
    Commented Sep 11, 2010 at 16:19
  • @mos - make sure sensitive equipment like computers are powered down before flipping the main switch.
    – ChrisF
    Commented Sep 11, 2010 at 17:03
  • 5
    The next step, after killing the main breaker, is to turn off all the circuit breakers, and power them back on one at a time. This will help you isolate a circuit that is giving you the problem. Commented Oct 13, 2010 at 16:04

Depending upon how interested you are, there are several home energy monitors on the market, some of which are DIY installs.

The Blueline Powercost Monitor is a definite DIY install (for the most common meter types). It is a little box which interfaces with the meter (even the analog style), and monitors the usage in real time. It integrates with Microsoft Hohm, and gives you real time statistics, recent usage history, fancy graphs, etc.

The other big contender is the TED 5000. This integrates with Google's competing service (PowerMeter). This is pretty much the same story (statistics, history, graphs, etc.). It is essentially an ammeter hooked up to the electric line coming in your house. Because of this, it is more accurate than the Blueline. The downside is that you have to open up the breaker box to install this (which may or may not be DIY for you).

Compared to the standalone ammeter (~$80), this is significantly more expensive (~$250). However, the usage statistics over time may help you to reduce your overall electric usage once you have found and eliminated the main hog(s) in your house.

More reading:
     Engadget Review of the Blueline - With some comparisons to the TED5000.

  • +1 for Blueline's products. See my answer at diy.stackexchange.com/questions/3836/how-can-i-audit-my-furnace/… for a personal account of using it (including some of the free Microsoft Hohm graphs it'll produce). Total cost to me was about $150.
    – BQ.
    Commented Jan 7, 2011 at 15:23
  • 1
    Microsoft's Hohm and Google's PowerMeter are now discontinued. Any alternatives here? Do these devices work with any other services? Commented Jul 12, 2012 at 20:50
  • I saw a Sense Energy monitor on Amazon. It’s a Wi-Fi enabled box you install in main circuit panel that gives readings sends to phone. I haven’t bought it it looks promising.
    – Danger14
    Commented Feb 6, 2022 at 20:11

One thing not addressed in your question is how many kW-hrs you are using compared to your neighbors. You can't just compare on dollars. In TX with the deregulated electrical industry, you could very easily be paying 2-3 times what your neighbors are paying per kW if you haven't checked it recently. Last summer I switched companies to get from ~$0.19 to $0.092, while keeping the 100% renewable energy sources that I had before. Go to www.powertochoose.org, a site set up by the TX Utility Commission, to compare rates.


Brultech has a solution that will show you how much each circuit uses. You might need an electrician to install it. It works like the ammeter but tracks usage over time.

  • This looks pretty interesting - any experience with it? Commented Oct 27, 2010 at 13:34
  • Not yet. I'm moving into a new house and haven't had a chance to order it.
    – Joseph
    Commented Oct 28, 2010 at 3:03

I want to add/link an answer I just gave today on another question: https://diy.stackexchange.com/a/133721/82083

tl;dr: In central europe it's very common that you can borrow power meters from your electricity company or from some environmental NGOs. May/may not apply to your location.


All the other answers are correct, I just wanted to add that most meters read and charge for apparent power which is a combination of true power(the actual power the device is using to do useful work) and the reactive power (the power drawn when the device pushes against the true power). In well designed fully working circuits the reactive power should be eliminated but if a compensating capacitor or choke coil is failing then the reactive power can double the apparent power and double your cost of running a particular device. Unplugging or isolating certain circuits in turn and monitoring what is being used compared to what you expect to be used will show where the problem is.

  • 1
    All meters for private homes are counting only reactive power, at least in European households. The Ferraris meter have coils for voltage and current at 90 degree phase angle, no torque is resulting with reactive power to turn the aluminum disc. Electronic ones do calculate the real power as well. As option some meters offer the display of apparent power and/or reactive power. In general, households are not paying for reactive or apparent power, but only for reactive power. In commercial buildings, the reactive power might be billed as well, which motivates for compensation measurements.
    – xeeka
    Commented Sep 28, 2019 at 10:03

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