# Help calculating how much it costs to run a small fan.



## MeLikeUmFire (Oct 11, 2011)

I am not good at math so i figure i could pic some of your electrician minds. We have gotten into the habit of turning on a small fan for our daughter to have some white noise while she sleeps. i am wondering how to compute how much it costs to run the thing? Its a small fan..it says on the fan its 60hz.....8 amp...prob runs 12 hrs a day.  I know it depends on how much i pay for my electric...can anyone give me an equation?


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## spirilis (Oct 11, 2011)

at 120vac, 8 amps is 0.96kW, times 12 hours/day is 11.52kWH/day, multiply that by your average cost per kwh to see how much it costs you each day.

so:

kwhprice * 11.52 = daily cost


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## maverick06 (Oct 11, 2011)

make sure you consider all the costs, not just generation, transmission, tax, etc (for me its $0.176)

So you get 120v*8 amps = 960watts/1000 = 0.96kw*12h = 11.52kwh/day*$0.176=$2.02

BUT a fan that runs at 120v 8 amps is HUGE... thats bigger than my whole house fan.... Maybe you ment 0.8 amps? that would be more reasonable, and just 20 cents per day... .

just put it inperspective, and get $/ year.... even at 0.8 amps for 12 hours is still $70/ year.... 

voltage x amps = watts. 

watts x time = watt hours 

watt hours / 1000 = kilowatt hours

that is how you are billed.


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## spirilis (Oct 11, 2011)

ah yeah good point, 8 amps isn't a "small" fan by any means :D


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## jimbom (Oct 11, 2011)

I think the ampere rating is 0.8 amp.  The OP tried to bold the decimal point, but I didn't notice it at first.


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## Village Idiot (Oct 12, 2011)

Another quick and easy way to see how much electricity is being used is to get something like a Kill a P3 - Kill a Watt. I picked one of these up for ~$25 a few years ago to figure out what my fridge, chest freezer, and sump pump were using so I could properly size a generator. It can show you how many amps a motor pulls on startup and how much power is used over time. I have since used it to measure all kinds of point uses of electricity in my house. It drives me absolutely crazy to see electricity being used in an unoccupied room.

If you want to go even further and monitor the whole house usage, there are options for that as well.  This past weekend I installed my TED 5000 (The Energy Detective) system in my new house. Had it in the old one and loved it. Though, I do find that I may obsess a little bit more about the electricity now that I can see how much it is costing me real time. The kids do get credit for being much better now that they can see how turning things off lowers the watts being used on the display.

Now that we will be using wood to supplement our heat, my family is looking forward to the warmer temperatures in the house. I am researching methods for monitoring gas usage, though that is a bit more difficult.

Water on the other hand is pretty easy. I have a few water metersI am considering  that have a nice output that I can monitor to track usage.

Don't tell my wife about this though. There is already enough eye rolling going on at my house and she may just hurt herself if she finds out about my plans.


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## maverick06 (Oct 12, 2011)

You can get the kill-a-watt to show peak? How? I havent figured that out on mine. I also put in a TED 5000 2 weeks ago, wonderful! It wont update the firmwre, but is really great! Already been able to make a few minor adjustments, havent had time to dive into it too much.


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## Village Idiot (Oct 12, 2011)

maverick06 said:
			
		

> You can get the kill-a-watt to show peak? How? I havent figured that out on mine. I also put in a TED 5000 2 weeks ago, wonderful! It wont update the firmwre, but is really great! Already been able to make a few minor adjustments, havent had time to dive into it too much.



The Kill a Watt does not have a max hold function, but with quick eyes and multiple runs with the device, you can get pretty close to identifying the max values. To make it more easy, I plug the Kill a Watt into a power strip or short extension cord (reduces potential voltage drop issues) so I can hold it in my hand and power cycle the device I am measuring. Then I average a few measurements and feel that I have the information I need.

I got my first TED 1000 a few years ago and recently upgraded to the 5000 for Mac compatibility. When updating the firmware, make sure that you are trying to use the correct version. You need to know if you have a 21 or 20 series device. The TED 5000 firmware page has the necessary information for doing the identification. Once you have the correct files, make sure you are instaling the gateway FW first. Finally, I have had mixed success with the specialized installation program. Upgrading via the Footprints webpage has always worked for me.


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## Hass (Oct 12, 2011)

When I saw 8 amps, I thought that had to be a MASSIVE FAN.
42" industrials only use 2-3amps and move a hell of a lot of air.

standard small table tops 6-8" or so are usually about 20 watts.
So maybe .015A
If it ran for 10 hours a day, (assuming she turns it on before she sleeps, and leaves it on when she's awake for a while) that's about 200 watts a day.
Probably somewhere around .10-.15/kWh... so maybe 2 pennies a day I'd guess?


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