anyone know how to read a meter? How much power is used every time that big horizontal spinny thing goes 'round? What do the dials mean, something in KiloWatt hours?
How much energy is consumed per one revolution of the disk will be stamped on the nameplate of your electricity meter. The other dials are typically calibrated in ones, tens hundreds, thousands and tens of thousands of kilowatt-hours. One kilowatt-hour is the amout of energy consumed by a draw of one thousand watts for one hour.
Meter Reading
Aint Google wonderful!
The dials are like an odometer: they each go from 0 to 9 and represent one fixed-place digit. They rotate in opposite directions. The reason for this is purely to keep the mechanism simple; since power meters are not designed to be read by simpletons like you and me, but by trained power company professionals, why bother with the extra gears to make them all turn the same way?
Usually there are five dials (so your meter can go up to 99,999 kw/h) but some old meters have only four. To figure out how much power you used in a given time period, just subtract the old reading from the new one. (Be careful when it loops back around to zero though!)
Good page, but it doesnt explain (on my first quick read) how much power is consumed per revolution of that spinning horizontal dial. Is that 1 watt hour per revolution or something?
It depends on your specific model of watt-hour meter–they are not all the same. See my post above.
Incidentally, the figure you’re looking for will probably be listed on the nameplate as “kH”; for example, “kH: 3.6”, which would mean that one revolution of the disk equals 3.6 watt-hours of energy consupmtion.
FYI
That big horizontal spinny thing is a eddy current motor that makes one complete turn every time a certain amount of power is consumed.
Others provide the details above
Energy. Not power.
The tricky part is when an indicator appears to point directly at a certain numeral, e.g., 6. The problem is that it may be slightly short of the 6 and thus represents the numeral 5. The way to tell is to look at the next dial to the right (less significant digit). If it points to 0, or slightly beyond, then the numeral to the left is a 6, so those two would be read 60. If it points to, or just past a 9, the numeral to the left is really a 5, so those two would be read 59. If it is recorded as 69, it can result in a substantial error (if it involves the more left-most dials).
This is a fairly common error even among experienced meter readers when they are tired, hungry, sick, or distracted by a viscous dog or scantily attired female. (Don’t know about female meter readers. 
)
Brady
Does anybody know why meters were designed like this? Why wouldn’t they make it so that all the dials go in the same direction?
As a EE working for an electrical utility, I had to combat this error all the time. When I taught Basic Electricity to linemen, technicians, etc., I would set them up by asking which they thought used more fuel: my 4X4 truck or my diesel VW Rabbit. They would invariably say my truck and would initially be dumbfounded when I said that it was my Rabbit. Finally, someone would realize that the reason was that I very seldom drove my truck (partly because of the poor fuel mileage).
The message I was trying to get across was that energy represents some measure of **how much work ** you can do with that fuel. Thus energy could be represented by a certain amount of fuel (e.g., a gallon of gas). Power is a measure of **how fast ** you are using up that fuel (e.g., horsepower). To know how much energy (fuel) you used, you would have to know **how long ** you were using that power.
Kilowatts are a (an electrical) measure of how fast ** you are using up energy, an thus represent power**. To find out how much energy you used, you have to multiply the rate (power) by **how long ** you used it. This is why, as a residential customer, your bill is for a certain number of kilowatt-hours.
I used to cringe whenever I saw something our public relations department put out that contained this error. (For some reason, they never had to take my course. :smack: ). I even saw a financial analyst on one of the major networks compare the fuel costs of generating one megawatt (sic) of electricity using various types of fuel. (I am not holding my breath to see if they want to take my course! 
)
HTH, Brady
Left out a little bit of trivia. A/C units are commonly advertized as so many BTU’s, e.g. 5000 BTU’s. BTU’s (British Thermal Units) are actually a measure of energy. The actual ratings should be in BTU’s per hour, the amount of heat (energy) that they will remove from a room in one hour.
Brady
They usually are correctly labeled BTU/hr on the unit rating plate and in the manual about nine times out of ten, but the ad copy is almost invariably wrong. Drives me crazy too, so I feel your pain.
Mr. Blue Sky, see the post by friedo above wherein he addresses your very question.
:smack:
The type of meter with the dials going in opposite directions used to be common in the UK. Over the last few years another, more logical, type has appeared. Looking very much like a car odometer picture ,they are much easier to read. New gas meters are also of a similar design.