Seems a bit extreme. That says that the power company would need not only a key to the meter box, but also a key to the business to get inside anytime they want. A situation that would seem to expose them to all kinds of potential security issues.
It also doesn't say that YOU cannot have a key as well.
Regardless of what is happening in other places, many of them in other countries as outlined below, have you asked the electric company if you can have a key?
Hi, Often saw in my working days, meter inside a box but it always had an opening(window) so one can see the reading and so on.
** The point being, if you are totally ignorant as to how the dollar amount on the electric bill is determined, the first place to ask questions is the company supplying the electricity and providing the bill. Once you get all those nasty details figured out, you'll have a better idea of how to go about verifying the numbers
"Home Guy" wrote
I'd agree with you if you were right, but in all likelihood, you are not. I've been hanging around USENET for about 15+ years now. I've seen too many question asked, answered, and later find that the real answer is something far different because important facts were left out.
Specifically the ratio of real power to real+imaginary power. ;-)
If the motors are fully loaded the PF will be close to one. A lot of unloaded motors will have a low PF, as will a pile of electronics (specifically ones with switching regulators), but for different reasons. Capacitors will correct the former but will do nothing for the latter.
No, that's real power being used.
Capacitors do nothing for start-up currents.
Not questionable at all. It makes perfect sense for large customers, as does charging for power factor. None of this has anything to do with the OP's problem, if he really has one, though.
In this case, I'm asking how a watt calculation made by taking an average RMS reading for a few minutes from a clamp-on RMS amp meter on a supply phase and multiplying that by 120 to get VA would differ from the "watts in use" as being measured by the utility's billing meter during the same few minutes.
The question did not involve the various uncertainties as to whether the meter is employing "demand-meter" metering, or the uncertainties as to whether or not extrapolating a few minutes of average current draw is representative of an entire month's usage.
The answer, as posted by a few sane people who looked at the original question and gave an actual answer, is that yes, VA can be considered as equivalent to watts when all loads are resistive and power-factor is unity (ie - 1).
To the extent that my facility's appliances, devices and equipment have non-linear (ie inductive) loads, my measure of VA == watts *will* be an over-estimate of what the meter is measuring during the time-frame of the measurement.
That over-estimation will most likely not exceed 10% because the worst offenders for having low power-factors are small fractional-hp electric motors, for which I have two (one in each bathroom of this building as ceiling ventilation fans) and for which I would estimate their use to be perhaps 3 hours per day. In addition to those two fans, the building's furnace has a 220 VAC furnace fan motor which I would estimate to be 3/4 to 1 hp and the daily usage (for the present time) to be 1 hour per day or less.
I've been using it since 1988 (that's about 23 years now).
And I've also seen far too many questions asked and then the thread is hijacked by others who want to take the question on a tangent because they don't know how to answer the original question but instead feel a compulsion to post something to prove they are worthy or relevant to the group.
In actuality, the larger the motor, the greater will be it's power factor.
Fractional HP motors (1/8, 1/4, 1/3, 1/2, etc) have low power factors (37% to 66%).
Motors above a dozen hp have power factors of 85% or better.
Those motors are only better because they are usually sized properly and are running near their rating. If you lightly load such a motor, it still can draw a lot of current, but out of phase with the voltage. Little real power is being used, but lots of VAs. Another way of looking at it is a lightly loaded motor is acting like an inductor. The more real mechanical load applied to the motor, the more real electrical power is required. The motor looks more and more like a resistor as the power reaches the design limits of the motor.
Because the cost to generate the electricity is small compared to the cost to deliver the energy. The cost to deliver the energy, in turn, is determined by the infrastructure needed (poles, transformers, generation capability, etc.). A commercial customer with even a short peak demand may require more infrastructure to support that demand than dozens of residential customers.
So what would you consider or where would you place the threshold for which demand metering should be used by a customer?
What monthly kwh usage would you consider "worthy" or significant enough for an electricity supplier to use a demand meter to cover this so-called significant cost of delivering this huge amount of brief peak energy?
Would you consider, say, 2000 kwh? Would a single month's total usage of 2000 kwh qualify a customer for a demand meter? Would 4 consecutive months of 2000 kwh be the line-in-the-sand for putting a customer on a demand meter?
Anyone with a 100 amp, single-phase service that is using their service at 50% for an entire month would tip the scale at a 4300 kwh bill. Hardly what I'd call justified for utilizing 50% of the smallest installable utility service.
How would you justify the infrastructure costs needed to supply such a paltry service such that demand metering is needed?
On 5/29/2011 8:04 PM, Home Guy wrote: ...
On the basis that it the assertion that it's not generation but transmission only that matters--it's both.
Given the restrictions on new generation facilities and tightening regulation on existing, if there's any growth in demand there's getting to be nowhere from which to get it.
Applying demand metering shifts (or at least increases) the interest of the user that previously hasn't ever cared by the only really effective behavior-changing device--the pocketbook.
It's not the monthly kWh usage that determines whether demand metering is used or useful. It's the *peak* usage and when that peak occurs. The infrastructure has to be built for the largest demand, not average. Where the threshold is placed is a different matter for each power company.
I don't believe any residential customers have demand metering, but I could be wrong.
Define "such small".
You wouldn't have demand metering with a 100A service. ...at least not a residential service.
yes you might. APS in Arizona offers demand metering to residential customers, (at least they did when I lived there)
The so called PEAK demand was based on the highest power used during any 60 minute period over the billing period. With demand metering, they lower the kWh rate but they charge you also for the peak. For example, with standard billing you might pay $0.12 per kWh. With demand billing you would pay $0.06 per kHW plus $5.00 per peak kWh. So for example if I used 100kWh during and a peak of 5 kWh during the month the charge would be $60 plus $25. If you are just a little careful you can save a lot of money. If you are just a little careless it can cost you a lot of money.
Also following this thread some of you seem to be mixing up power factor and demand billing, they are two different things. Some industrial billing plans bill by kWh, peak kWh AND power factor.
Mark
I wouldn't say it that way. It's very material in that (as you clarify) it sets the rate for the usage. Just nit-picking to make it clear to the OP that there are two very clearly different factors to consider in business rates that are different from residential rates. A power blip that ended up turning every device on simultaneously (a rare situation - except for X-10 users ) could be an extremely costly event. Why? Because peak demand rates are set by the maximum power ever used during the metering period. The OP could have easily changed the dynamics of his billing by plugging in a couple of new space heaters at exactly the wrong time. That sort of event could easily explain why the OP finds himself owing a lot more money than last year even though the kWh used could be virtually identical.
I've learned (the very hard way) that with posters here from all over the world, many of the things I thought were customary nation or world-wide are just local quirks. (-:
"Deserves got nothing to do with it" - Unforgiven
No, I beg to differ. I always feel much more comfortable encountering service personnel and such knowing as much as I can learn elsewhere. I believe the OP has learned a great deal from this thread and could get to the point where an encounter isn't even necessary. His bill probably holds the sad tale of a one time excursion into a higher rate zone that's cost him big time. I'll bet he now becomes very aggressive managing his peak load.
I would suggest dropping $25 for a basic Kil-O-Wat plug in meter
Which is why I recommend the Kil-O-Watt meter. You can measure each device (except hard-wired ones) and get a true reading (wattage or V/A) of its instantaneous power consumption or the consumption over a period of time. A clamp meter is a good way to measure the items hardwired to the circuit panel, but it's pretty lousy for determining wattage or power consumption over time for stand-alone devices.
- Bobby G.
AND:
I have seen way too many people propose entirely stupid questions and postulate insane methods to try and answer them...
Yet, those people, like yourself, keep coming back here and asking their questions leaving out important material facts because the person seeking an answer either didn't know such information was important or had any bearing on the answer they desired or they are asking something they are totally ignorant about... Getting defensive about your question when people attempting to help you by asking for clarification of certain aspects and more details about your situation is a clear indication that you are asking for the information for illicit purposes or are just plain trolling...
Feeling like you need to offer *correction* to people who reply to your newsgroup posting when they offend some etiquette guideline is just showing that you are too focused on the format of the message rather than the content... Chill out...
I didn't know that in addition to being an expert on accounts payable that you were also an internet psychologist -- good to know...
~~ Evan
On 5/29/2011 10:03 PM, Robert Green wrote: ...
I get no feeling OP has really learned a thing...it seems to all just pass over as it doesn't fit into the preconceived notion.
His complaint is he has a few months w/ very high usage; not that the $ amount is high at relatively low total usage (as would be the symptom of a demand-induced premium). I think the likelihood he actually has a demand meter is very low.
From the numbers on usage he posted before, it appears to be a fairly consistent usage w/ a couple of months extreme outliers. Both of those are early in different years; my hypothesis is that the other months are, for the most part, estimated rather than actually read and the one annual blip is the catchup because they've not updated the average usage to reflect actual since it was set up (probably before OP bought the building).
--
And 4300 is more than 2 x 2000.
Did you read the link?
A 100 amp service is 4 times what you need to draw 2000 kwh in a month.
@Bobby:
Or the OP could have an an electrician install an emon demon like RBM suggested in his main service panel and the reading from it and the amount of electricity the OP is being billed for should always agree...
@Home Guy:
You are too focused on the total billed number of kWh to see why a demand meter is used for electrical services with a main disconnect rated over a certain amperage...
A customer with a steady draw (demand) of 2.7 KW over 30 days to end up being billed for 2,000 kWh over the course of a billing period is *MUCH* easier for a power company to serve than a customer whose draw is 500 KW a couple of times during the same billing period and winds up with the same 2,000 kWh of use...
To serve the second customer whose demand is erratic and might come at a time when the local power grid is overloaded requires the power company to provide beefier service lines in that area and have the capacity to accommodate that erratic load without tripping safety devices in the power grid or browning out other customers...
You just don't seem to understand that the greater the amount of power a customer needs to use at the same time (peak demand) is more important than the total of the kWh that customer is billed for during any given period... Whether you use 1 KW for 2,000 hours or 2,000 KW for 1 hour makes a difference in how the power company serves you as far as equipment and capacities...
Again whether or not you have a demand meter depends on the purpose of the occupancy and the amperage rating of the main disconnect... A home with a 100 or 200 amp main service would usually not have a demand meter, but a home with a 1,200 amp main disconnect very well might have a demand meter installed...
~~ Evan
I've located some PDF documents that my local utility has on-line.
I have to have a "12-month average demand" equal to or more than 50 kW, or have a 12-month rolling kwh consumption greater than 150,000 KWhrs in order to have a demand meter. 150,000 kwhrs divided by 12 is 12,500 kwh per month, which is about 4 times my average monthly consumption.
So no, I don't think I've experienced any one-time excursion into a higher rate zone, at least not in terms of being demand-metered (if indeed there are any other ways of entering a higher rate zone).
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