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Questions
about Electric Meters
Where does electric go
after it passes through any appliance in my home? I
have often heard it returns to the grid? Isn't that
silly! I'm lost!
-- Big Bad
Barry, Pennsylvania, Jan. 2005
This doesn't really havy anything to do
with saving electricity but it gives me an
excuse to use a good analogy I came up with.
Pretend a giant is sitting in the yard at the
power plant. Or it can be Shrek if you prefer.
Also pretend that instead of electrical wire, we
use dental floss. The giant is holding a piece
of dental floss in one hand, and that leads to
your house, through your house, then back out to
the power plant and into the giant's other hand.
So you've got a giant holding an enormous strand
of dental floss that forms a complete loop,
starting in one hand and ending in the other.
With me so far? Good.
Okay, so now the giant pulls on one end of
the floss. As he does that one hand comes
towards him and the other goes away from him.
Then he pulls on the other end to do the
opposite. Pretend he's exercising with the
floss. He does this really fast, reversing
direction 120 times per second, or 60 times per
second if you count doing both directions as one
set.
That's how household electricity works. It
doesn't start at the power plant, run through
your house, and then go back to the power plant.
Instead what's happening is the power plant is
pushing electrons down one end of the wire, then
they reverse it and push from the other end. The
electrons in the wire get rubbed back and forth,
like a scrub brush. This is what transfers
energy to the appliances you're running.
Does my meter charge me
for volts or for watts? Do higher voltage
appliances cost more to run?
-- Various readers
The electric company charges you for
watt-hours, not volts. To figure volts you use
the fomula Volts x Amps =
Watts. A device that runs on 240V will use
half as many amps as an identical device that
runs at 120V, so the wattage will be the same --
and so will the cost.
The kinds of appliances that use 240V
tend to be energy hogs, like air conditioners
and electric clothes dryers, so running those
appliances will cost you. It's not because 240V
costs more, it's because you're running
energy-gobbling appliances.
If you read all this and you think that 240V
costs more than 120V then you didn't read
carefully enough and should re-read the
above.
Question: I just
noticed today that my electric meter is not
spinning at all. I don't know how long this has
been going on and we are in the middle of a billing
cycle. I was definitely using electricity in the
house when I happened to notice the meter (heater
was on, computers, lights, etc.) What should I
do? -- T.
Allen, Ft. Worth, Texas
Contact your utility company.
I'm using
your formula
for looking at my electric meter to measure the
usage of my
appliances, and
I'm wondering what is the 7.2 on the meter, and the
3.6 multiplier, and why divide by seconds? I'm sure
my neighbors think I've been in the sun too long
since I'm running in and out of the house reading
my meter. --
David Jones, Scottsdale, AZ, Aug.
2002
(1) Different meters spin at different
rates, so that's why you use the kH factor
specific to your meter. The kH factor is
basically the size of your meter.
(2) You divide by seconds because you're
measuring the energy used for a specific amount
of time. If you didn't include the time in the
equation, the number you got would be
meaningless. (If the answer was "400
watt-hours", would that be every 12 seconds,
every four hours, or every three months?)
(3) The 3.6 is to put your answer in the form
of kilowatt-hours. Without the 3.6 you
have the number of watt-seconds. Here's
how it works:
There are 3600 seconds in one hour (60
seconds x 60 minutes). So multiplying your
answer by 3600 would give you the amount of
electricity for an hour. But it would still be
in the form of watt-hours, not kilowatt-hours.
To convert to kilowatt-hours you divide by 1000.
So all in all you're multiplying by 3600 and
dividing by 1000. Note that 3600/1000 is 3.6, so
our shortcut for multiplying by 3600 and
dividing by 1000 is to just multiply by 3.6.
[Thanks to reader Jim Haywood for figuring
out what the 3.6 is for.]
My power bill doubled
in kilowatt hours and I cannot figure out why (8kWh
in March 2002, to 15kWh in March 2003). This
surprised me because I have not been using my heat
or air conditioning and my habits have not changed.
My place is just a simple one-bedroom apartment. I
had maintenance check out my hot water heater and
refrigerator to make sure they were working
properly and they said everything was fine. I
called my power company and they came out to check
the meter, and they said everything was fine. Then
I find out my neighbor's power bill has also
doubled to $211 (she lives across the hall from
me). Do you think there is a problem with my
meter-- Kate Baumann, April
2003
It's hard to say exactly where the
problem is until you test it, but it's
possible that the problem is with the
meter. You can definitely test the meter, but
there's a bit of work involved.
First, turn off every circuit breaker in your
apartment and then see if your meter is still
spinning. If so, your meter is definitely
broken. I would first videotape your turning the
breakers off and that the meter still spins so
you have evidence in case you have a hard time
getting a refund from your electrical utility
for being overcharged.
If the meter stopped cold when you turned off
all the breakers, then turn them back on again,
but turn off and UNPLUG everything in your home.
If there's no switch for the electric hot water
heater, then keep the heater's breaker off. Make
sure the meter is still stopped cold. If it's
spinning again, turn off all the breakers again,
and then turn them back on one at a time to
isolate which one is causing the meter to spin.
Once you've isolated that breaker, see if
there's a device that's plugged in or a light
that's turned on that's eating up power. If
you're convinced that there is nothing that
should be drawing power, your meter may be
broken. Videotape as suggested above and contact
your electric utility.
If you can get the meter to stop cold with
the breakers on, then turn one item back on,
like a light, and then look at the meter to
measure how much
electricity it's using. If the meter says
it's using more than about 20% of what it should
be using, then there may be a problem with your
meter.
If the light measures correctly, then turn it
off, and start turning on other items and
measuring them. At this point your assumption is
that the meter is correct, but that one of your
devices is drawing more than it should, such as
your hot water heater or your refrigerator.
Good luck, and let me know what you find
out!
I've been trying to
figure out why I consume so much power each month
(950 kWh), since I'm not at home much, my
refrigerator is new, and the AC is barely run. I
unplugged everything (not just turned them off) but
my electric meter was still spinning at about 1 rpm
(~400 watts). So then I cut all the breakers
off, but the meter was still spinning!
Could the meter be broken? If it is, who would I
contact about that? If I can prove to the electric
company that it has been broken since I bought my
house will they refund my money? --
Shaun Cooley, CA, July 2001
[I suggested that Shaun first
document the problem with a video camera and
have a licensed electrician confirm the problem,
so that he had proof, and THEN contact his
electric utility company. The electric utility
said the meter was broken and put in a new one,
but refused to refund the money he paid for
electricity he never used. His only option for
getting a refund at that point would be to take
them to court or seek arbitration; I don't know
if he ever did.]
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