Electric Consumption


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Old 01-20-04, 03:54 PM
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I'm at the boiling point on "Power Companies"!

If I am at the wrong forum please transfer! I am posting here because it is "Electric" and receives the most hits!
Doe's anyone have or know where I can get a device to record my daily use of electricity relative to the electric meter or any other way?
I absolutely do not mean something with an interaction with my power company in any way shape or form!!
I am not interested in any other interaction regarding my extreme anger regarding the subject.
Changeling
 
  #2  
Old 01-20-04, 06:58 PM
P Michael
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I have a hunch that you may be upset over high electric bills. If you doubt that the meter is accurate, you can call the power company and they should check it out. However meters are pretty reliable.
Thus the conclusion is that you are using too much electricity. Do you have electric heat? Electric cold water heater? Electric stove?
If so, then stop taking showers, eat out at Burger King and wear thermal underwear.
~Peter
Note: there is a company in Hileaha, Florida which sells electric meters. Spelling is probably wrong but close.
Note: Do an energy audit of your house.
 
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Old 01-20-04, 07:02 PM
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Why not just buy your own generator, cut loose the wires to your house, and generate your own electricity. That way you will never pay the power company again. It's completely legal and you will soon discover the true cost of electrical power generation without consulting with anyone from the power company.
 
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Old 01-21-04, 06:53 AM
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You can buy your own electric meter and have an electrician connect it such that all the load passes through it (probably not code legal and fairly expensive). It's easy to go through a lot of kw.... my electric bill is $80 a month... and it's only a 1000 sq ft apartment with all gas applicances. And this is in the winter when the AC is not running.
 
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Old 01-21-04, 09:51 AM
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I know of no 'off the shelf' device that can record the entire load of a home. There are however, plenty of sources for items that can show the usage of a single, low power ( < 1500 watts) device.

If you want to see if the meter is reading electricty that you aren't using, that's easy. Simply flip the main breaker in your panel box. Make a note of the meter reading, and come back in a hour (or less, if you see the dial still spinning). If the reading has changed, then you how a power 'leak' somewhere.

If you suspect the meter is bad, the power company will be more than happy to check it for you. They want it to provide an accurate reading as much as you do.
 
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Old 01-21-04, 11:12 AM
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http://www.imsmeters.com/ is one such manufacturer. There are several more manufacturers that I've seen. I'm pretty sure Grainger sells electric meters, I think made by GE.

It's an option...but it's much easier and cheaper to convince the Poco to swap their meter.

There are very few things that can go wrong in a regular residential meter however... so far I haven't found one "bad" meter that will read more electricity than used. I've found some that will read less... but who wants to report that?
 
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Old 01-21-04, 12:12 PM
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First like was said pull the main and go watch the meter. The next thing is rent or get a tattletale and put it on the main line and see what volts you do get comeing in all the time for 24 hr.

You know as the volts go down the amp draw goes up on like the stove and water heater elements and you pay for amps.
Also there is an amprobe recorder you can put on.

We just had a guy here in heat & cool. High electric bills for the past 4 years. Had the power company come out each year go over the home said everything was ok. the power company guy this year found that one of the strip heaters in the heatpump has been on all the time


So I say LOOK arond ED
 
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Old 01-21-04, 12:58 PM
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Ed Imeduc, thanks for the reply. Where do I get the items you talk about, tattletale and amprobe you refer to? Can I install or do they have to be installed by an electrician?
Changeling
 
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Old 01-21-04, 01:29 PM
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I have a Fluke 123 scope meter that you can put a current clamp on and measure the current. You can then record those readings to a computer data file every second, or at any interval you like. You can do the same with voltage. It's possible to download the the whole data file to Exel, and calculate your power usage over any time interval you like. Everything is available off the shelf from Fluke. It's just fairly expensive. I've used the system a couple of times to measure power consumption.
 
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Old 01-21-04, 03:54 PM
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Its like what do you want to spend. Id start with a good amprobe.
This will tell you how many amps all the things there draw and if they are on at all. will also read the volts for you. ED
 
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Old 01-21-04, 04:34 PM
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Originally posted by Ed Imeduc
You know as the volts go down the amp draw goes up on like the stove and water heater elements and you pay for amps.
Also there is an amprobe recorder you can put on.



==>You do NOT pay for amps! You pay in watthours. Basically you pay for wattage.Stoves, waterheater elements, dryers and electric heat are pure resistive loads. With purely resistive loads when your voltage drops... so does your current!!
 
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Old 01-21-04, 07:43 PM
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For heater elements it doesn't matter anyway. If your voltage is high, the heater element dissipates more power; but you do not pay for power, you pay for energy (power times time: watt-hours). Since the heater element is dissipating more power, it does not run as long so the total energy you use is the same.
 
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Old 01-22-04, 12:16 PM
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I thought I asked simple question, let me re fraze it.
I need a way to check on the power companies meter readings. I would like to do this automatically. I would love to be able to download the data to a computer. Is there something like that available? If so, what is a rough estimate of the cost of the equipment and where do I get?
Changeling
 
  #14  
Old 01-22-04, 01:16 PM
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Our reply was also somewhat simple. What makes you believe that the meter is malfunctioning? Instead of spending the time and effort to verify the POCO's values why don't you just ask them to replace the meter? It's free, and most will do it after some persuasion.
 
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Old 01-22-04, 01:18 PM
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Lightbulb power

Watts are volts x amps..
you pay for enegry power X watt-hours

So it still comes back to. The amp draw on anything.

like I said when you use more amps you have to pay more.

Now on a chomalox unit in the furnace not all use it. The stove and the water heater If the voltage drops or goes down they pull more amps. So you will get a higher electric bill
ED
 
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Old 01-22-04, 01:42 PM
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Ed:

Please explain how when the voltage drops across a resistive load like a water heater element the current goes up? Have they repealed Ohm's law recently without me noticing?
 
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Old 01-22-04, 01:59 PM
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A resistor is rated by it's "watt" or power rating. Since it's purely resistive (or almost) and since P = V x I, if the voltage drop the current will increase to keep the same P. A 1000W heating element will always try to give out 1000W. At a lower voltage the elemet will draw more current.
 
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Old 01-22-04, 02:10 PM
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Amp out a chromalox strip heater and drop the voltage--the amps will go up . Then amp out a chromaloy wire heater in a unit drop the voltage and the amp draw will go down. what can I say been there done that. ED
 
  #19  
Old 01-22-04, 02:17 PM
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This seems to be a common misconception.

The current I (in amps) through a resistor is set by its resistance R (in ohms) and the voltage across it V (in volts) such that I=V/R. Since the resistance is constant, as the voltage decreases the current decreases.

Heating elements are specified in watts not because they dissipate constant power independent of voltage but because they dissipate rated power at a nominal voltage. If the voltage goes down a heating element will draw less current and dissipate less power (fewer watts).

If you don't believe me, check this out on Chromolox's web page:
http://www.chromalox.com/technical/p...electrical.pdf
Read the first two paragraphs "Ohm's Law" and "Voltage and Wattage Relationship".
 
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Old 01-22-04, 03:29 PM
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Everyone makes the assumption that in a resistor the resistance remains constant. That usually isn't true in one used as a heating element. The resistance is one value when the element is cold and another when the element is at the nominal operating temperature. Many materials have a negative temperature coefficient, that is, when the temperature goes up the resistance goes down. Some materials have just the opposite. In both cases you have to know the temperature to know the resistance. Years ago there used to be a resistor used in radios that when hot had a much lower resistance than when cold. The device was often used in series with the filament circuit of the tube. When the radio was first turned on the device offered a high resistance to limit the inrush current and keep that shock from buring out the tubes so fast. As the device heated up from the current flow its resistance would fall to a low value to limit the voltage drop across it so the tubes would have full filament voltage deliverd to them. All materials have some sort of temperature coefficient, but most common ones have a coefficient value so low that it is usually ignored.
 
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Old 01-22-04, 03:41 PM
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Look in Graingers catalog for a 2TS92. The cost is $895. It will analyze and record your power usage. You can hook the device to your Windoz computer to do all the recording chores. That should work nicely. I can't vouch for the equipment, however, because I do the same thing with a Fluke 123 scope meter. That device costs a lot more, but it does more, and I do know that it will work on a single phase line to measure & record the current flow and voltage. It can record those value samples to a computer using FlukeView that can be analyzed later.
 
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Old 01-22-04, 04:25 PM
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As mentioned, there are a lot of complicating factors:
  • Resistance isn't really a constant.
  • Not much is 100% purely resistive
  • Etc
Nevertheless, it is a gross distortion to suggest that current goes up as voltage drops to keep the power constant. This just isn't so. There is no magic force that keeps power constant. A 60-watt light bulb only uses 60 watts when provided with the voltage stamped on the bulb. Lower the voltage and it will only be a 50-watt bulb. The bulb just isn't smart enough to hold the wattage at 60. Same is true for your water heater element. Same is true of resistance heating. A 1000W heating element does not "try" to give out 1000W. It's not smart enough to "try" to do anything. The element is passive and pretty stupid.
 
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Old 01-22-04, 07:15 PM
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Jughead:

I agree with you regarding tempco, but in the case we are discussing here I don't think it is relevent - by the time a heating element gets to operating temperature I think that its tempco has flattened out quite a bit (tempco is not a constant, either).

John:

Thanks for the reinforcement. Since you brought up passive loads, there are some active loads which can draw more (or at least constant) current as the voltage drops:

(1) Electronics with linearly regulated power supplies (most audio equipment) will tend to draw constant current independent of voltage. For these devices power dissipation still goes down when voltage goes down, just not as fast as a resistive load.

(2) Electronics with switching power supplies (computers, televisions) tend towards constant power - these can draw more current as the line voltage decreases.

I'd think in most homes the dominant loads are resistive - lights and heat. Lights will cost more to run as the voltage goes up; heaters will cost the same (assuming they have thermostats) since when the voltage goes up they run less often (lower duty cycle).
 
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Old 01-22-04, 07:37 PM
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Ed,
Look at the rating plate on any electric range. There is a 208v kwattage and a 240v kwattage rating. The 208v is always lower than the 240v wattage.
 
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Old 01-22-04, 09:31 PM
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I stand corrected... it's not often I deal with "simple" situations like this. You're all correct, if there is nothing to foce the load to stay constant the power/current will drop as the voltage. Most of the work I do involves power supplies, and the load is always there, and always constant. If the input voltage drops the current will always increase because the load does not change. There is really no load on a heating element or a light bulb. Therefore there is nothing to push the current higher.
 
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Old 01-22-04, 09:49 PM
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Excellent post John Nelson!

I do believe however that most loads in a home are fairly close to having a power factor of 1. The big loads are mostly resistive heating like water heaters, dryers, ovens, electric heating elements and of course lighting.

After all Im sure if there were lots of reactive loads the power company would go to the trouble of charging for them. We'd have VoltAmphour meters instead of watthour meters.
 
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Old 01-23-04, 07:16 AM
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OH BOY

I think I opened a can of worms here.

All that I know is the paper work with the units that had a chromalox unit in them gave a amp draw for 220V that was lower than the amp draw for 208V.
When the nichrome wire units paper work would show an amp draw for 220V and it would show a lower draw for 208V

Ill open another can of worms
When we would get a replacement for a element of nichrome wire. They where all the same like door springs. But it was how long you pulled it apart or out in length. For more or less BTU of heat????????????????????? ED
 
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Old 01-23-04, 08:27 AM
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Ed:

The Chromolox web page seems to list different part numbers for 208V applications than for 240V applications. Probably the sheet they send covers both parts. A heater which is designed for 1000W at 208V would certainly draw more current (i.e., it would have a lower resistance) than a different heater designed for 1000W at 240V.

See this one for example: http://www.chromalox.com/products/prodinfo/en/skr.html
 
 

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