Is my KWH calculation correct?

[AaronLS]

I moved into this house about 4 months ago. I was billed for almost
1000 KWH electricity last month. The previous two months I lived here
I was billed about 1500 KWH per month. I had been too busy to pay
attention to may bills, but I was amazed. The house is only 600
square feet, which is about the same as the apartment I lived in, and
the electricity usage there was half what I'm paying now.

I have no new appliances, and as a matter of fact I no longer have a
dish washer(although I own one that I plan to install).

The house was built in 1945.

I have a frig, washer, dryer, electric oven, microwave, electric water
heater, and 1 computers I leave running 24/7 which idles most of the
time and has a 300 W power supply, but my understanding is it only
draws the wattage that the sum of it's components use. It is nothing
but a linux file server, and the hard drive is almost never active.

I use 2 other computers maybe 4 hours out of the day.

If I am billed 1000 KWH in a month, by my calculations I am using
about 1400 watts per hour on average. I divided 1000 KWH by 720
hours(number of hours in a month) and got 1.3888 KW. Is that correct?

If so then I need to get one of those devices for measuring
electricity usage. I am also thinking I should unplug everything and
go and see how fast my meter is running. Is it possible there could
be a short in my houses wiring that is drawing power constantly?

[danny burstein]

Post by AaronLS
If I am billed 1000 KWH in a month, by my calculations I am using
about 1400 watts per hour on average. I divided 1000 KWH by 720
hours(number of hours in a month) and got 1.3888 KW. Is that correct?

aside from your misuse of terminology, yes. That is,
your _average demand_ is _1.4 kilowatts_, not 1400 watts per hour.

That's about twice what I'd guess from your description
(very back of envelope) of what you've got there.

Post by AaronLS
If so then I need to get one of those devices for measuring
electricity usage. I am also thinking I should unplug everything and
go and see how fast my meter is running. Is it possible there could
be a short in my houses wiring that is drawing power constantly?

A "short" pulling enough current to notice would likely
have your house on fire by now.

Spend the $25 or so and get a "kill-a-watt" meter. That'll
let you check the spot, and also cumuative, power usage
of items plugged into the circuit.

And look around for things that aren't right. For example,
if you have a hot water leak... plenty of other things
can be draining power without it being obvious.

[m***@worldnet.att.net]

Post by AaronLS
I moved into this house about 4 months ago. I was billed for almost
1000 KWH electricity last month. The previous two months I lived here
I was billed about 1500 KWH per month. I had been too busy to pay
attention to may bills, but I was amazed. The house is only 600
square feet, which is about the same as the apartment I lived in, and
the electricity usage there was half what I'm paying now.

By any chance, is this half of a duplex? If so, go turn off all your
circuit breakers and/or open the main switch on the fuse box and see if
your neighbors complain that their lights went out. :)

Is there any chance that there is a load someplace that you don't know
about yet? Like in a shed/garage/workshop, or maybe heat tape for water
pipes under the house, or a light in the attic, or something like that.

Post by AaronLS
The house was built in 1945.

You didn't say, but if your IP address is any indication, you appear to
be in the Tallahassee, Florida area. This implies maybe higher than
average use of air conditioning. If your apartment was nearby, then you
still may have a problem - on the other hand, many apartments are rather
newer than 1945 and so will be better insulated.

Post by AaronLS
[...] 1 computers I leave running 24/7 which idles most of the time
and has a 300 W power supply, but my understanding is it only draws
the wattage that the sum of it's components use.

This is basically true. There are also a few watts lost to heat in the
power supply. I put a Kill-a-Watt meter on my desktop PC and I could
actually watch the consumption go up a few watts when I did a 'find /'
(which runs the hard drive extensively).

Post by AaronLS
If I am billed 1000 KWH in a month, by my calculations I am using
about 1400 watts per hour on average.

Well, just 1400 watts average (not "per hour").

Post by AaronLS
If so then I need to get one of those devices for measuring
electricity usage.

Like Danny mentioned, the "Kill-a-Watt" meter is useful (besides being a
fun toy). Sometimes you can find them locally, but I got mine from
Amazon. There are a couple of different companies that make them.
Basically it's a little watt-hour meter that you plug into the wall and
then plug your appliance into it. If the meter you get has no cord, you
may also want to buy a short but stout extension cord; one of those 3'
or 6' ones they sell for room air conditioners is good. This is so you
can put the meter where you can see the display, instead of under the
desk or behind the refrigerator or whatever.

Note that for something like a table lamp, which draws full power all
the time, you can just turn on the lamp, take a reading on the meter,
and turn the lamp off. For something like a refrigerator or computer
that uses variable amounts of power, it's better to let it run for
several hours to get an average. The meters I have seen at least have a
clock that starts from 0 hours 0 minutes when you plug it in, so you
don't have to worry about reading the meter at exactly 7 PM or whatever;
you can just read the power used and the total hours:minutes from the
meter and do the math.

Post by AaronLS
I am also thinking I should unplug everything and go and see how
fast my meter is running.

Unplugging everything is the first step. Turning off all of the
breakers or fuses is another. If the meter still runs with all the
breakers or fuses turned off, then either there is another breaker or
fuse panel you don't know about, or something odd is going on. If you
turn the breakers/fuses back on one at a time, you *might* be able to
find out which circuit has the heaviest users on it.

Post by AaronLS
Is it possible there could be a short in my houses wiring that is
drawing power constantly?

Possible but unlikely. If it was drawing that much power, you would
probably have smelled something getting warm by now.

Matt Roberds

[TWayne]

Post by m***@worldnet.att.net

Post by AaronLS
I moved into this house about 4 months ago. I was billed for almost
1000 KWH electricity last month. The previous two months I lived
here I was billed about 1500 KWH per month. I had been too busy to
pay attention to may bills, but I was amazed. The house is only 600
square feet, which is about the same as the apartment I lived in, and
the electricity usage there was half what I'm paying now.

By any chance, is this half of a duplex? If so, go turn off all your
circuit breakers and/or open the main switch on the fuse box and see
if your neighbors complain that their lights went out. :)
Is there any chance that there is a load someplace that you don't know
about yet? Like in a shed/garage/workshop, or maybe heat tape for
water pipes under the house, or a light in the attic, or something
like that.

Post by AaronLS
The house was built in 1945.

You didn't say, but if your IP address is any indication, you appear
to be in the Tallahassee, Florida area. This implies maybe higher
than average use of air conditioning. If your apartment was nearby,
then you still may have a problem - on the other hand, many
apartments are rather newer than 1945 and so will be better insulated.

Post by AaronLS
[...] 1 computers I leave running 24/7 which idles most of the time
and has a 300 W power supply, but my understanding is it only draws
the wattage that the sum of it's components use.

This is basically true. There are also a few watts lost to heat in
the power supply. I put a Kill-a-Watt meter on my desktop PC and I
could actually watch the consumption go up a few watts when I did a
'find /' (which runs the hard drive extensively).

Post by AaronLS
If I am billed 1000 KWH in a month, by my calculations I am using
about 1400 watts per hour on average.

Well, just 1400 watts average (not "per hour").

Post by AaronLS
If so then I need to get one of those devices for measuring
electricity usage.

Like Danny mentioned, the "Kill-a-Watt" meter is useful (besides
being a fun toy). Sometimes you can find them locally, but I got
mine from Amazon. There are a couple of different companies that
make them. Basically it's a little watt-hour meter that you plug into
the wall and then plug your appliance into it. If the meter you get
has no cord, you may also want to buy a short but stout extension
cord; one of those 3' or 6' ones they sell for room air conditioners
is good. This is so you can put the meter where you can see the
display, instead of under the desk or behind the refrigerator or
whatever.
Note that for something like a table lamp, which draws full power all
the time, you can just turn on the lamp, take a reading on the meter,
and turn the lamp off. For something like a refrigerator or computer
that uses variable amounts of power, it's better to let it run for
several hours to get an average. The meters I have seen at least
have a clock that starts from 0 hours 0 minutes when you plug it in,
so you don't have to worry about reading the meter at exactly 7 PM or
whatever; you can just read the power used and the total
hours:minutes from the meter and do the math.

Post by AaronLS
I am also thinking I should unplug everything and go and see how
fast my meter is running.

Unplugging everything is the first step. Turning off all of the
breakers or fuses is another. If the meter still runs with all the
breakers or fuses turned off, then either there is another breaker or
fuse panel you don't know about, or something odd is going on. If you
turn the breakers/fuses back on one at a time, you *might* be able to
find out which circuit has the heaviest users on it.

Post by AaronLS
Is it possible there could be a short in my houses wiring that is
drawing power constantly?

Possible but unlikely. If it was drawing that much power, you would
probably have smelled something getting warm by now.
Matt Roberds

From the "possible but not probable" side, several years ago we noticed
a sharp spike in our electric usage. After a bunch of searching, it
turned out to be the underground cable that used to power a shed, years
ago, about a hundred feet from the house was the culprit. No idea what
happened underground there, so I just located (after some searching, I
might add) the wires, cut them, put the ends in a junction box, taped
capped and labeled it. Our bills went back to normal. In this part of
the country it's not unusual to find old electric connections to old
outbuildings that may not even exist anymore. Fortunately mine did so
it help to locate the wires. Worth looking around, at least, to make
sure there aren't any such things there. IIRC I measured something like
9 amps going into the ground. Too bad I'm not a fisherman anymore; in
wet weather, I bet the crawlers were right there for the picking<g>.

Twayne

[AaronLS]

Post by TWayne

I moved into this house about 4 months ago.  I was billed for almost
1000 KWH electricity last month.  The previous two months I lived
here I was billed about 1500 KWH per month.  I had been too busy to
pay attention to may bills, but I was amazed.  The house is only 600
square feet, which is about the same as the apartment I lived in, and
the electricity usage there was half what I'm paying now.

By any chance, is this half of a duplex?  If so, go turn off all your
circuit breakers and/or open the main switch on the fuse box and see
if your neighbors complain that their lights went out.  :)
Is there any chance that there is a load someplace that you don't know
about yet?  Like in a shed/garage/workshop, or maybe heat tape for
water pipes under the house, or a light in the attic, or something
like that.

The house was built in 1945.

You didn't say, but if your IP address is any indication, you appear
to be in the Tallahassee, Florida area.  This implies maybe higher
than average use of air conditioning.  If your apartment was nearby,
then you still may have a problem - on the other hand, many
apartments are rather newer than 1945 and so will be better insulated.

[...] 1 computers I leave running 24/7 which idles most of the time
and has a 300 W power supply, but my understanding is it only draws
the wattage that the sum of it's components use.

This is basically true.  There are also a few watts lost to heat in
the power supply.  I put a Kill-a-Watt meter on my desktop PC and I
could actually watch the consumption go up a few watts when I did a
'find /' (which runs the hard drive extensively).

If I am billed 1000 KWH in a month, by my calculations I am using
about 1400 watts per hour on average.

Well, just 1400 watts average (not "per hour").

If so then I need to get one of those devices for measuring
electricity usage.

Like Danny mentioned, the "Kill-a-Watt" meter is useful (besides
being a fun toy).  Sometimes you can find them locally, but I got
mine from Amazon.  There are a couple of different companies that
make them. Basically it's a little watt-hour meter that you plug into
the wall and then plug your appliance into it.  If the meter you get
has no cord, you may also want to buy a short but stout extension
cord; one of those 3' or 6' ones they sell for room air conditioners
is good.  This is so you can put the meter where you can see the
display, instead of under the desk or behind the refrigerator or
whatever.
Note that for something like a table lamp, which draws full power all
the time, you can just turn on the lamp, take a reading on the meter,
and turn the lamp off.  For something like a refrigerator or computer
that uses variable amounts of power, it's better to let it run for
several hours to get an average.  The meters I have seen at least
have a clock that starts from 0 hours 0 minutes when you plug it in,
so you don't have to worry about reading the meter at exactly 7 PM or
whatever; you can just read the power used and the total
hours:minutes from the meter and do the math.

I am also thinking I should unplug everything and go and see how
fast my meter is running.

Unplugging everything is the first step.  Turning off all of the
breakers or fuses is another.  If the meter still runs with all the
breakers or fuses turned off, then either there is another breaker or
fuse panel you don't know about, or something odd is going on.  If you
turn the breakers/fuses back on one at a time, you *might* be able to
find out which circuit has the heaviest users on it.

Is it possible there could be a short in my houses wiring that is
drawing power constantly?

Possible but unlikely.  If it was drawing that much power, you would
probably have smelled something getting warm by now.
Matt Roberds

From the "possible but not probable" side, several years ago we noticed
a sharp spike in our electric usage.  After a bunch of searching, it
turned out to be the underground cable that used to power a shed, years
ago,  about a hundred feet from the house was the culprit.  No idea what
happened underground there, so I just located (after some searching, I
might add) the wires, cut them, put the ends in a junction box, taped
capped and labeled it.  Our bills went back to normal.  In this part of
the country it's not unusual to find old electric connections to old
outbuildings that may not even exist anymore.  Fortunately mine did so
it help to locate the wires.  Worth looking around, at least, to make
sure there aren't any such things there.  IIRC I measured something like
9 amps going into the ground.  Too bad I'm not a fisherman anymore; in
wet weather, I bet the crawlers were right there for the picking<g>.
Twayne

Thanks everyone.