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
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
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
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
Just for the heck of it go after hours and turn off your main breaker
with friends watching building.
I had a customewr at a local shopping mall they had electrical
troubles and found a connection from their meter powering public
spaces in the mall, seemingly left over from the malls construction in
the 60s. Tenants on that meter had been paying a big chunk of the
malls electric bill..
This was identified one night when the customer had a fire. The fire
department pulled the meter blacking out a big piece of the mall.
The mall claimed no knowledge:( I believe there was a lawsuit,,,,,,
That doesn't sound like it was a professionally managed "mall"...
Sounds more like it was being run by people like Home Guy...
All the malls I have seen inside of have entirely separate
switchgear to power tenant versus house circuits...
You are the one being the UseNet douche here guy...
Commercial electricity is metered based on peak demand
I don't care where you are in the US, it is the way federal
laws on the buying and selling of energy are written...
That first given established, you totally blew off the source
of the *most* qualified electrical advice on this newsgroup
supplied by RBM because you didn't like the 'format' of
his posting method and so called 'etiquette' violations
when your postings actual content is way out in orbit
of some other planet...
Now let us address the specific issues you seem to
-- Your electrical meter is locked within a cabinet
enclosure where *you* the consumer are unable
to observe the cumulative readings on it at various
points during the billing period to determine any
abnormal usage issues...
That is *highly* abnormal for a meter to be locked
inside a cabinet like that where the indicator of
the amount of electricity you are going to be billed
for is concealed from you... I would place a call
to the local public utilities official and explain your
situation and that your meter is hidden away from
you where you can not read it but once a month
when the power company unlocks its cabinet,
that install does not sound kosher -- at the very
least an observation hole can be made in the
cabinet so you can see your meter...
-- Is there only *one* tenant in this "building"
as it sounds like there is only one meter...
That is an abnormal way to pay for electricity
in a commercial building if there are multiple
tenants irregardless of whether the lease
terms are gross or net (NN) (NNN)...
With one meter all you would be able to do
legally without some sort of sub-metering
involved (the emon demon that RBM mentioned)
is divide the total cost by the square footage
of the building and apportion it to the tenants
based on the tenant's square footage...
-- You are so caught up in the minutiae of how
you can home brew a way to calculate your
power use by simply calculating all the wattage
of all the devices and appliances used in your
occupancy that you seem blissfully unaware
that many things require a "starting current"
like your furnace motor and the ballasts for
those exterior light fixtures on the mechanical
timer -- with a commercial electrical service you
get billed for the highest simultaneous demand
for current as well as the simple kWh of usage...
It sounds to me like you have a lot to learn before you
even attempt to dispute anything with anyone...
It is also waaaay to late to dispute charges for
electricity billed like over a year ago -- there is usually
a time limitation which covers when you can challenge
a utility bill, I have never heard of one that let you go
more than 60-90 days after the billing date to initiate
Good luck man -- hope you can return safely to
earth since you are clearly in orbit somewhere with
all of this...
My first guess would be that the logical explanation for 1915.26
up 4 times would be that it is some form of an ESTMATED reading
used when they didn't take an actual reading. The odds of that number
showing up 4 times from a true reading would be very low. And if it
has, I'd suggest using it to play the lottery.
A meter reader always pays a visit to the building either on the first
or second work-day of the month. He reads both the electric and water
meter (both are inside the building and can't be read from the
outside). I know that because we have to escort the reader to the
utility room, and I'm the one that does it about 1/2 the time, and when
someone else does it they tell me they did it.
There is never a month that goes by without someone coming to read the
Then I'd have a conversation with the electric company and
ask them to explain how 4 months in a year can have
the exact same usage, down to the hundreth of a kwh. And how
there are two other month pairs where the usage is exactly
the same down to less than 1 kwh. It's possible but the
probablities are clearly very low. Even if you had a truly fixed
load that never varied, you'd expect more variation than
that due to some months having more days.
possible and we could calcu
I agree the billing usage numbers look very suspicious.. I would
contact the power company, bypassing the regular customer service, by
calling the chairman's office and working from there. You can usually
get that sort of information from the investor information section of
the stock listing for the company.
I am wondering why you are trying to do this? First what is the power
factor in this circuit? If your goal is to increase efficiency to result
in savings, look into that. If you suspect meter is inaccurate you can
request for a replacement. Newer digital meters are more dependable and
accurate. Even my cabin located in the boondogs have digital power,
natural gas meters. You already know typical power consumption pattern.
So what is the purpose?
So I shouldn't assume that, say, a bank or three of florescent lights
won't necessarily draw a constant amount of current?
Or a dozen PC's?
The neutral is not smaller (physically) than the other 3 cables. It's
the same size.
Most charts I see only go as large as AWG guage size OOOO (almost 1/2
inch diameter). In my case, the cables running from the meter to the
distribution blocks (a run of about 7 or 8 feet) are at least 1 inch
diameter (OD). The conductor diameter is at least 7/8".
So if I don't multiply my VA number by the power factor, then I'm
OVER-ESTIMATING my KWh calculation by 5 or 10%.
Why does my utility apply (add) a 5% "correction factor" to the KWh
measurement that comes from the meter?
You know what? You ought to monitor frequency. Usually it is not 60Hz,
the lower it shows power factor is getting worse. Ideally load should be
pure resistive which does not exist in real world. They are mostly
inductive load. There is such a thing called Pf correcting device to
improve efficiency. My SIL owns/operates mechanical moulding business
based on CAD/CAM. His average monthly bill is pretty constant. The
amount of monthly bill is pretty predictable. Other source of energy his
plant use is NG, mainly for heating.
You're pushing a very big rock up a hill to nowhere.
Your meter will give you little useful information.
You need to KNOW the phase.
Sticking your finger in your favorite orifice and pulling out a power
factor number is just that...a useless number. You don't
even want to think about the orifices you find here.
Why do you care?
A decision tree is often helpful.
If you think the equipment is faulty, you should enlist the power company.
I've found 'em to be very knowledgeable and helpful. They have the
equipment to determine whether your meter is faulty. A friendly
conversation with customer service should get you a call from
a real engineer. If it turns out to be faulty, make sure you
get calibration numbers off the old system so you can negotiate
If you think they're intentionally screwing you, you need to hire
an electrician with the equipment to measure WATTS. That's what you
pay for. Measuring VA is an exercise in futility. Your "finger"
ain't gonna hold up in court anyway.
You might be able to get some advice from the local electrical
If you think one of the tenants is charging their electric car
when you're not looking, your amp meter can point you in the right
I've used current clamps into a computer to log AMPS. Useful
for determining relative consumption from the same load...in
my case it was a water heater.
RMS amps is better than peak or average amps, but still not
a short path to WATTS...well, in the case of a water heater,
it is, but that's a special case of resistive load.
Depending on how the power meter's made, you can get cheap wireless
monitors that you might get the utility to let you clamp
on the meter...but that will have the same systematic
errors that the meter has. But it might help you find
any clandestine loads at odd hours.
Newer digital readout meters have an infrared light that blinks in concert
with the load. Mine is one blink per watt-hour. I programmed
a pda to read out and log consumption in real time. Again, for
my relative use. It has same systematic errors as the meter.
But you still gotta be able to "see" the meter...or put a fiber
optic cable to the outside.
You can buy clamp-on current transformers that also hook to the volts
and measure REAL power accurately. But it's much easier to pick up
the phone and have the power company help you.
The question about the 5% adder is one for customer service.
Did I mention...rock..hill...futility?
mike used improper usenet message composition style by unnecessarily
I should not see a huge spike in monthly usage during a month when our
hvac usage is practically zero. Investigating the reasons for this
spike is not path to nowhere.
An unnecessarily dramatic statement.
To say that a clamp-on amp meter can't give useful information is
To the extent that my aggregate power factor is less than .95 or .9,
yes, then I need to know the phase.
Are you suggesting that my effective power factor is likely to be less
What is the power factor of 10 to 20 year-old florescent lamp ballasts?
Or a 1 hp, 220 VAC fan motor? Or a 10 year old refridgerator? Or a
typical desktop PC power supply?
Those are the largest (and probably only) non-resistive loads in
Because I pay the bills. What a stupid ass question that was.
I've already stated that I've contacted them, and that I expect to
encounter difficulty in having them ever admit that their metering
equipment could be faulty or even undertake a process to evaluate the
meter, but I will pursue every course of action and give them every
chance to determine that.
In the pages and pages of materials and contracts that exist for this
utility, describing all manner of service obligation and liability,
billing, etc, I find nothing in print that defines a process whereby a
billing meter is tested or what is done if a meter is found to be
There is absolutely nothing I can find in writing even contemplating the
possibility of a meter that does not measure correctly.
I believe that issue is a political "hot potatoe" for all municipal
electricity suppliers, something they'd rather not have to deal with and
hence they largely remain silent about it.
I believe that they never "intentionally" screw anyone, but that instead
they put up a front that their meters are always correct, all the time,
and reinforce that by not mentioning the possibility of erroneous meter
operation anywhere in any printed material they make available, let
alone define in writing a process or methods to test a meter that the
client believes is suspect.
The worst I can do by measuring VA is to OVER-ESTIMATE my watts used by
5 or 10% - unless you think it's likely that my aggregate power factor
is less than 90%.
Making my own measurements would be a first-step. I never said I'd use
those measurement in court (that is your hyperbole again).
If indeed it got that far, then I would investigate my options have
having an acredited third-party measurement performed, and that would
only happen if my local utility did not perform their own tests that I
was satisfied was unbiased and accurate.
Ah, the true picture emerges -- an accounts payable rep who thinks
that because they pay the bills they understand how everything
You clearly lack the technical expertise to do anything about this
on YOUR side of the meter...
You seem to not understand the regulations which protect consumers
and control how power is sold in your state -- therefore you are
of your potential remedies in this "situation" if one really exists...
Instead of spending your time researching something actually useful
which might shed some light on what is actually going on (if anything
really is at all) you have chosen to ask stupid questions which are
clearly not on the proper wavelength to make any sense to someone
who actually understands electrical issues AND you are chasing after
something *YOU* can do which would support *YOUR* claim that
your electrical meter is not functioning correctly when there may
in fact be a procedure to follow which has already been defined by
the public utilities commission (or equivalent in your state) which
would almost always involve bringing in an uninterested third
party with the proper credentials and equipment to assess what
if anything is happening in this whole convoluted story...
It seems whenever you get some sound advise that would make
sense in the real world, you attack the contributor because the
person didn't respond with the specific answer you were looking
for in your especially preferred format... So you critique based
on newsgroup etiquette and posting format rather than the
supplied content -- keep doing that and you will be properly
labeled as a troll and written off as such...
BOTTOM LINE>>>>every single dime.
Sounds like OP is Scrooge, will be only happy when he gets free power.
His building may be 100 years old containing industrial revolution era
Proper course of action would cost $$$ which is not in his book. My take
on this thread.
Investigating is good. The method you're using is the rock
Get a tool that can do the job...and he works for the power company.
Yes, I am.
If you have a bunch of CFL lights and nothing else running, your
aggregate PF can be 0.6.
During the day, when the lights are off and motors are running, it
might be 0.6 in the other direction. The power meter only cares about
what's happening NOW.
There's a lot of legislation in place or on the way to make NEW
stuff do internal power factor correction. But it's gonna take a while
to make a difference.
Power factor is a mythical number that assumes that voltage and current
are both perfect sine waves that are out of phase.
Take a look at the load from your computer. You might find that
it's a bunch of narrow spikes that bear no resemblance to sine waves.
A "kill a watt" meter will give you a power factor number, but the
crest factor may be WAY bigger than 1.
The only number that makes ANY difference is the one after the $ on your
Quit messing around and get the power company out to look at it.
Show them the evidence you're bitching about here. Only they can
do anything about it.
What's on the paper is inconsequential until you get into a court of law.
Fret over that when it happens.
CALL THE POWER COMPANY...you don't appear to have the skills or
equipment to make a challenge.
It's my assertion that GETTING THE POWER COMPANY TO INVESTIGATE
is the first step.
The second step is to call whatever agency regulates the power company.
Attempting to measure it yourself is way down the list. You ain't got the
equipment to prove 'em wrong.
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