# I has a wattmeter! :-D **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [August 19, 2007, 6:25am UTC](https://boards.straightdope.com/t/i-has-a-wattmeter-d/416120 "2007-08-19T06:25:10Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Nanoda](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Nanoda](https://boards.straightdope.com/u/Nanoda)\ **Post date:** [August 19, 2007, 6:25am UTC](https://boards.straightdope.com/t/i-has-a-wattmeter-d/416120/1 "2007-08-19T06:25:10Z")
I’ve wanted one for ages, and finally decided I had to have one. Loads of research, 11 phone calls and a dozen websites later, I’ve taken delivery of a [P3 Kill A Watt](http://www.p3international.com/products/special/P4400/P4400-CE.html) wattmeter. (And 2 of my co-workers ordered them from the same place directly afterward :P). After making up a spreadsheet and testing almost everything in the house, I’ve so far discovered that at 10c/kWh, my refrigerator is costing me ~33$/year, my freezer 39, and my computer (which I knew to be a large drain and am replacing shortly) just over $200. ``` Interestingly, the HP 6110 all-in-one that I scrounged from a repair pile at the office and just use for occasional scanning draws a constant 8 watts (7$/year) even when it's turned off. That got unplugged right away, though the [unexpectedly low](http://boards.straightdope.com/sdmb/showthread.php?t=432641) 2 cents/load on my washer is still a mystery to me. Anyhow, you can't borrow it 'cause I'm not done with it and have 3 people already lined up, but if you check your library, they might loan you one. :) ``` ---
**Author:** ![if6was9](https://avatars.discourse-cdn.com/v4/letter/i/e47c2d/32.png) [@if6was9](https://boards.straightdope.com/u/if6was9)\ **Post date:** [August 19, 2007, 8:07am UTC](https://boards.straightdope.com/t/i-has-a-wattmeter-d/416120/2 "2007-08-19T08:07:44Z")
Isn’t that what the meter on the side of your house is? Free for the using? ---
**Author:** ![Ice\_Wolf](https://avatars.discourse-cdn.com/v4/letter/i/dfb087/32.png) [@Ice\_Wolf](https://boards.straightdope.com/u/Ice_Wolf)\ **Post date:** [August 19, 2007, 9:40am UTC](https://boards.straightdope.com/t/i-has-a-wattmeter-d/416120/3 "2007-08-19T09:40:20Z")
[QUOTE=if6was9] Isn’t that what the meter on the side of your house is? Free for the using? [/QUOTE] The meter on the side of houses measures the total electricity used. This thingy of **Nanoda’s** measures the electricity usage and efficiency of each appliance within the home. Only other way other than buying one of those is to consult the power company about which appliance is chewing up the most of the power. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [August 19, 2007, 12:19pm UTC](https://boards.straightdope.com/t/i-has-a-wattmeter-d/416120/4 "2007-08-19T12:19:29Z")
\>Only other way other than buying one of those is to consult the power company about which appliance is chewing up the most of the power. What? You can turn everything off except for the one appliance, or perhaps whatever else it needs to function (eg your well pump for washer testing). The power company, of course, could refer to published lists of typical costs for appliances, like the things they reference in stickers on the appliances at the store. Other than that, the power company has no idea what your freezer in particular is doing. Now, how does this meter know how appliance performance changes during the year? For example, the freezer costs much more to run in summer than winter, because it pumps heat to a warmer environment, it condenses more moisture out of whatever air infiltrates, and it might even get opened more often when you’re hot. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [August 19, 2007, 1:25pm UTC](https://boards.straightdope.com/t/i-has-a-wattmeter-d/416120/5 "2007-08-19T13:25:46Z")
Interesting website. No prices given that I could find. Also there is the Kill A Watt EZ with its stunning 98% accuracy. That item in your house might be costing you $100 per year to run, or it might be $2, or even $198. Isn’t that about the same as you would get with a dartboard and a blindfold? :rolleyes: ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [August 19, 2007, 5:17pm UTC](https://boards.straightdope.com/t/i-has-a-wattmeter-d/416120/6 "2007-08-19T17:17:23Z")
\>Also there is the Kill A Watt EZ with its stunning 98% accuracy. Silly fellow. Obviously, this means it’s right 98% of the time. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [August 19, 2007, 5:26pm UTC](https://boards.straightdope.com/t/i-has-a-wattmeter-d/416120/7 "2007-08-19T17:26:25Z")
[QUOTE=Napier] \>Also there is the Kill A Watt EZ with its stunning 98% accuracy. Silly fellow. Obviously, this means it’s right 98% of the time. [/QUOTE] Well following that line of reasoning the model you bought advertises accuracy of 0.2% which would mean it is right two-tenths of the time. Hope you didn’t pay more than about 29 cents for that kind of accuracy. I worry when a company can’t even get the specs of what they are selling correct. 😃 ---
**Author:** ![Ice\_Wolf](https://avatars.discourse-cdn.com/v4/letter/i/dfb087/32.png) [@Ice\_Wolf](https://boards.straightdope.com/u/Ice_Wolf)\ **Post date:** [August 19, 2007, 5:46pm UTC](https://boards.straightdope.com/t/i-has-a-wattmeter-d/416120/8 "2007-08-19T17:46:37Z")
[QUOTE=Napier] What? You can turn everything off except for the one appliance, or perhaps whatever else it needs to function (eg your well pump for washer testing). The power company, of course, could refer to published lists of typical costs for appliances, like the things they reference in stickers on the appliances at the store. Other than that, the power company has no idea what your freezer in particular is doing. [/QUOTE] I’d say the use of a device such as that which the OP is so pleased with eliminates the “Let’s see, I’ll turn off everything except the fridge – test – now everything except the hot water – test – now the hair dryer …” kind of thing. I’ll ask a friend later today what he thinks – he’s in the appliance trade. This sounds like a version of what the trade uses as a matter of course to test the function of the appliances they repair and sell – without having to switch everything off, then on again, in the hope of economy. I wonder how **Nanoda’s** getting along with the purchase, BTW? ---
**Author:** ![Nanoda](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Nanoda](https://boards.straightdope.com/u/Nanoda)\ **Post date:** [August 19, 2007, 9:26pm UTC](https://boards.straightdope.com/t/i-has-a-wattmeter-d/416120/9 "2007-08-19T21:26:07Z")
**Ice Wolf** : Your appliance tester sounds like a [clamp multimeter](http://www.metermantesttools.com/mmusen/products/MM+AC6X+7X+AD105.htm) (which I also have, but which is a PITA and doesn’t log over time). I would challenge anyone to use their electricity meter to calculate single-appliance useage. I tried it last winter when my bill skyrocketed and I suspected my furnace motor of being the culprit. Each try involved 10 minutes of set up, a flashlight, my stopwatch, many minutes standing in the cold, and lots of math, and was still inconclusive. [QUOTE=Napier] how does this meter know how appliance performance changes during the year? [/QUOTE] For that, you just plug it in for a few days and record the reading. I’ve been recording my 'fridge for 135 hours now and it’s used 5.09 kWh, which my spreadsheet shows is $33.05/yr. I got mine from eBay for 27CAD all told, but people in the 'States should be able to get one for a bit less. I think it’s going to pay for itself in short order. It’s [ul][li]confirmed that my PC needs replacing[/li][li]found that my scanner costs me almost 1/4 of what my 'fridge does, saving me some $$$ right there[/li][li]saved me time looking at a new washer (which I was idly considering) since it’s _way_ not worth it for me[/li][li]going to help me with appliance purchases. If, say, a showroom TV draws 20 watts instead of \<1 when it’s “off”, I’m going to skip it.[/li][/ul]And that’s just _my_ place. I’m taking care of the cat at my parents next week, and they can’t stop me from testing everything they own. 😃 ---
**Author:** ![Ice\_Wolf](https://avatars.discourse-cdn.com/v4/letter/i/dfb087/32.png) [@Ice\_Wolf](https://boards.straightdope.com/u/Ice_Wolf)\ **Post date:** [August 19, 2007, 10:36pm UTC](https://boards.straightdope.com/t/i-has-a-wattmeter-d/416120/10 "2007-08-19T22:36:54Z")
[QUOTE=Nanoda] **Ice Wolf** : Your appliance tester sounds like a [clamp multimeter](http://www.metermantesttools.com/mmusen/products/MM+AC6X+7X+AD105.htm) (which I also have, but which is a PITA and doesn’t log over time). [/QUOTE] _That’s_ the one! (I’ve seen something else in the shop too, but I’m not into that field at all.) Cheers, **Nanoda**. Long may you test! 😃 ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [August 20, 2007, 1:40pm UTC](https://boards.straightdope.com/t/i-has-a-wattmeter-d/416120/11 "2007-08-20T13:40:08Z")
\>For that, you just plug it in for a few days and record the reading. I’ve been recording my 'fridge for 135 hours now and it’s used 5.09 kWh, which my spreadsheet shows is $33.05/yr. Yes, but, last week my fridge was pumping heat to my unconditioned kitchen which spends days in the 80’s, and I was opening the door for ice and cold seltzer several times a day to keep myself cool. In six months it will be pumping heat to 10 or 20 °F cooler surroundings, and I won’t be using ice for anything and won’t be drinking as much cold seltzer either. So, the fridge will use more electricity during summer tests than during winter ones. ---
**Author:** ![Nanoda](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Nanoda](https://boards.straightdope.com/u/Nanoda)\ **Post date:** [August 21, 2007, 12:20am UTC](https://boards.straightdope.com/t/i-has-a-wattmeter-d/416120/12 "2007-08-21T00:20:46Z")
Well, you’re going to have to take representative samples for a few different temperatures and estimate. I’m planning on checking again in January, along with adding data for an electric space heater I happen to have. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [August 21, 2007, 2:05pm UTC](https://boards.straightdope.com/t/i-has-a-wattmeter-d/416120/13 "2007-08-21T14:05:59Z")
[QUOTE=Nanoda] I got mine from eBay for 27CAD all told, but people in the 'States should be able to get one for a bit less. [/QUOTE] My Grandfather-in-law rents one from the library. I’ve been meaning to get over there and rent one as well. But I’ll probably just buy one. They sell them around here (Harbor Freight) locally. I think it’s about $30.