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Old 06-16-2009, 11:12 AM   #1
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Electric Meter


What is the best way to check the accuracy of the power companies meter. Had it checked by the power company, they said it is OK. I have my doubts.

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Old 06-16-2009, 12:24 PM   #2
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First, turn off everything in the house for as long as you can stand it and make sure the meter does not advance.

If you pay 16 cents/kwh and your meter is off 1% in their favor and you use 1kw all the time they owe you $14/yr, plus interest.

You'd need a meter 5x or 10x more accurate than PoCo's meter, and I can't readily find a published spec. for this number.
If you can find a stable 10A load, like a toaster, you could measure the volts and amps going into it, probably to 0.1%. A 100A, 240v load would be better, like the aux heat coils for a heat pump. Everything else should be off.
To get high accuracy, measure and record the values until you get bored. Volts x amps x time = watt-hours. 240v on average at 100A on average for 0.1 hour = 2.4 kwh.

If you find credible evidence for "an error" in their favor and make a fuss, they'll be watching you! Along these lines, the Gas Company [GaCo?] tried to entrap me after I called them on their bad behavior, on behalf of a customer of mine.
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BTW, if it really is an "error" half the time in the long run it would be in favor of the consumer. I doubt that this will be the case. By this standard, politicians almost never make an error, regardless of them calling it a "mistake" or that they "mispoke."


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Old 06-16-2009, 04:42 PM   #3
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Thanks for the info..
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Old 06-16-2009, 05:04 PM   #4
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It is hard to turn OFF everything in the house without going to the Main. There is always something pulling power e.g. Doorbell Xfmr.
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Old 06-16-2009, 05:13 PM   #5
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Is this a Condo, Apt, House?
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Old 06-17-2009, 02:15 AM   #6
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Most resdential meter useally are pretty acture ( correct ) but once a while you will get a slipped up meter.

The only way you will see if the meter is functioning correct is shut off the main breaker ( i know you hate to reset the daxmmed clocks ) if the meter stop rotating for few mintues then it should be ok but still rotaing then you have issue with your system.

But if you really want a load test get couple of 150 watt indscent bulb and run the X amout of minutes { make sure everything else is off in the house to get the correct reading } IIRC there were a link or goggle how to read the meter and also how to test the meter load { for resdentail side only }

Merci,Marc
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Old 06-17-2009, 07:32 AM   #7
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"The amount of energy represented by one revolution of the disc is denoted by the symbol Kh which is given in units of watt-hours per revolution. The value 7.2 is commonly seen. Using the value of Kh, one can determine their power consumption at any given time by timing the disc with a stopwatch. If the time in seconds taken by the disc to complete one revolution is t, then the power in watts is
P = 3600 x kh/t
For example, if Kh = 7.2, as above, and one revolution took place in 14.4 seconds, the power is 1800 watts. This method can be used to determine the power consumption of household devices by switching them on one by one."

So if you're looking for a 1% error, 10w, then t = 3600 x kh/P = ~ 43 minutes.

http://en.wikipedia.org/wiki/File:Electrical_meter.jpg

The 7.2 designation is at the four o'clock position.

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Old 06-19-2009, 11:08 PM   #8
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Don't know what your local rules are, but all the Utility Commission standards I've seen don't even consider a meter out of calibration unless it is more than 2% off. If it is an induction disk meter, the odds are much greater that it will be slow (to the consumers benefit) than fast (to the utilities benefit).

Our shop typically tested around 1200 meters a year and in over a decade, I can count the number of meters that were fast (over 2%) on one hand. Of those, most were 2 to 3%, one was 9% and the only one that was significantly off (30% fast) was because the house had taken a direct shot of lightning (all the wiring in the house was melted) that had negated the residual magnetism of the meter's damping magnet.

If you have a high bill complaint and have already had the meter tested, your time will be much better spent finding out how you are wasting energy.
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Old 06-20-2009, 07:05 AM   #9
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Note that light bulbs, heaters, etc. are not suitable by themselves for measuring current flow or watts used. There could be a plus or minus ten percent variation from one to the next even of the same brand. But you can use them to get a rough idea.

The resistance of a light bulb or heater depends on the internal temperature. So you cannot easily predict the current draw by measuring when the item is turned off. (And you must never set the meter to ohms or continuity and measure resistance when the power is on.)

You need precision test equipment if you want to complain about a fast running meter.
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Old 06-20-2009, 07:41 AM   #10
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Quote:
If you have a high bill complaint and have already had the meter tested, your time will be much better spent finding out how you are wasting energy.
Ayuh,... Exactly....
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Old 06-20-2009, 07:54 AM   #11
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Quote:
Originally Posted by SKIP4661 View Post
Had it checked by the power company, they said it is OK. I have my doubts.
Why???

I know our POCO takes high bill complaints seriously.



Quote:
Originally Posted by WFO View Post
If you have a high bill complaint and have already had the meter tested, your time will be much better spent finding out how you are wasting energy.
Another +1 from me as well.
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Old 06-20-2009, 09:02 AM   #12
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I'd imagine that companies in general would make "errors" in their favor as long as the amount is small, to keep the outrage at a minimum should they be discovered.
Who's to stop them? Capitalism rules!

This is how car salesmen work; a few dollars of profit hidden here, a few dollars hidden there.
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Old 06-21-2009, 10:23 AM   #13
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Quote:
Originally Posted by SKIP4661 View Post
What is the best way to check the accuracy of the power companies meter. Had it checked by the power company, they said it is OK. I have my doubts.

I don't take offense at this (well....maybe a little ), but just for the record, after 35 years in the business, I have never been party to, or seen anyone else, falsifying a meter test. And that's with four different companies.
There's really no reason to. For one, as noted, induction disk meters are extremely stable, accurate devices that if and when their accuracy declines, it is generally in the customers favor. Fast meters are a rarity, believe it or not.
And for a company dealing with millions of dollars in energy costs on a monthly basis, refunding or crediting a residential customer his rightful share is not big deal.

And for what it's worth, when we do a meter test, we usually stay and do exactly what has been described here....we help the home-owner go through his house looking for reasons for the high usage.

But let's take this a step further. A meter is not the only component of a bad bill. On apartment complexes, services get mixed up quite often and getting billed for your neighbors usage is much more common than a erroneous meter.
Meters are simply misread (although this should have been caught at the meter test).
AMR (automated meter reading) systems often fail. Did the electronic reading match the mechanical register? Admittedly a problem if you only have an electronic register, but billing/consumption histories can be looked at to see if there have been sudden changes.

But far and away the most prevalent cause of a high bill is, something you are depending on to work, isn't.

Bad thermostats, leaking seal on refridgerator door, dust-clogged coils on a refridgerator or AC, leaking water well or water heater tank, strip heat coming on with the cooling (yes, this happens more than you'd think), or (also VERY prevalent) just using too much of everything. There is no free lunch....if you want your house to be 65 degrees in the summer, ya gotta pay for it!

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