Figuring energy consumptions and costs
This page show you how to read the meter supplied by your utility company for basic appliances.
people become more conscience about the amount of power they consume I think
it is time to share what I know about how to read your total household
A lot of people can read their meter to tell how many Kilowatts they have used in a given time, but I would bet that not too many know how to tell what kind of power is being consumed at any particular moment in time. So I am going to cover how to read the fine scale of your meter that you probably didn't know you had.
To do this you are going to need a pencil, paper, stopwatch, your electric bill to find your Kwh cost, and a calculator to do your figuring.
First go out to you meter and look on the face of it. You will see the
letters Kh and a number.
you know the 7.2 means 7.2 Watt-hours for each rotation of the metallic
disc in the meter.
Now the math:
We are going to use the average 7.2 like the meter shown above as our example.
There are 60 seconds in a minute, and 60 minutes in a hour. So 60 times 60
Meters Wh per revolution is 7.2.
The 25920 (or whatever number is right based on the Wh number of your meter is the base number that will be used from now on. So write the correct number down for all other calculations.
Now turn off all unnecessary things in your house. TVís things that would not be on if you are not home.
Go out to you meter with your stopwatch.
Wait for the disc to line up the reference mark with the front reference
line on the meter.
Lets say for example that it took 38 seconds to make a full turn.
Take you reference number that matches your meter. Mine being 25920 and divide it by the 38 seconds it took to make a revolution.
25920 divided by 38 seconds equals 682 watts per hour of consumption.
So how much is your house costing you per hour and per day with nothing but the basic stuff running?
can look on your electric bill and you will see what the cost of a
Kilowatt-hour is. Lets say for example that it is 9.5 cents per
Kilowatt-hour. sometimes shown as(.095)
682 X 9.5 = 6.479 by the way that is 6 point 479 "cents" of a dollar so
add a ď0Ē in front .06479
Now take the .06479 cents per hour cost and times it by 24 hours in the day.
.06479 times 24 equals 1.55496 which tells you that your house running the basic stuff costs you 1.55 per day.
Now lets fire up something big like the AC or electric stove and go time a revolution of the disc again.
Lets say that your AC causes your disc to spin at a rate of 1 revolution per every 8 seconds.
Take you base number 25920 divided by 8 seconds per revolution equals 3240 watts per hour. Or 3.2 Kw per hour. If you know that your ac runs on average of 14 hours per day. You can figure your cost per day like this.
3240 watts per hour times 14 hours of run time equals 45360 Kilowatts-hours
for its total run time.
Now take the total run time consumption of 45360 Kilowatt-hours, which we need to divide by 1000, to get figure the actual Kilowatts consumed since a Kilowatt is 1000 watts.
45360 divided by 1000 equals 45.36 kilowatts in total consumption
Then multiply 45.36 by the 9.5 cents per Kilowatt-hour you pay and you will know what it costs to run it on an average 14 hour day.
NOTE: to figure your cost
of the total Kilowatt hours used you will need to use .095 instead of 9.5.
45.36 X .095 = $4.3092 total cost per day, or 4 dollars and 30 cents per day to run your AC.
That doesnít sound too bad until you times that by the 30 day billing cycle.
$4.30 times 30 days per month equals 129.00 dollar per month added to your basic consumption we figured earlier.
Now you know why your bill goes up so much in the summer time.
You can use this system to figure the cost of any appliance one your side of the meter. once you know your basic draw you can subtract that from any other appliance you turn on and read to have an exact usage of that appliance.
Lets break that down since we have enough info to do that.
the AC along with the basic other stuff drew 45360 Kilowatt-hours.
Subtract what we know is our basic draw we figured first which was 682 from
Now you know how to test each appliance without having to unplug and place it on a separate meter.
Summary of math equations used:
60 seconds in a minute, times 60 minutes in an hour equals the amount of seconds in an hour. 3600
The meters Kh number (commonly 7.2) times the 3600 seconds in an hour for your base number of 25920 to figure your Kilowatt-hours used at any given time.
Number of seconds of a revolution of disc, divided by the above number (which commonly would be 25920) to give you watts per hour consumption of an added appliance or house.
Anything less than 1000 is just watts per hour, anything over 1000 is Kilowatts per hour which would need to be divided by 1000 to figure cost. 10000 / 1000 = 10 Kw.
Closing note: This is not 100 percent accurate for some loads such
as your Air Conditioner. The reason why is your AC kicks on and draws
more amperage/wattage at startup, then it levels out to a steady constant
draw. Use this information as a way to figure the steady constant draw
and the average costs of items, not as a way to dispute a Kwh or two on your