Utility Meter Accuracy

Well I have to admit that I'm stumped with an energy audit I've been working on for the past two months. Perhaps someone can point me in the right direction...

My client contacted me concerned that his electric bills were atrocious. They were, to the tune of 34,680 kWh per year (average monthly at 2,890 kWh, and a baseline of 2,347 per month!). And after my first visit to his home, it was very obvious to me that, although he has a big house (3700 sq-ft), he and his family of four were energy frugal, being careful to shut off lights when not in use, using power strips for entertainment centers, etc.

He was particularly concerned about the phantom consumption when he and his family would leave for several weeks at a time. When they did he'd shut off everything but the alarm system. And even then he'd see a bill of 1900 kWh for that month, and for what?

So I dove in deep, taking this on as a personal project, since he'd had an auditor from the utility company come out previously and they couldn't find anything. One of the first things I did was to install a PowerSave EnviR monitor on the two mains into the main circuit panel and let that thing collect data for exactly two weeks. I compared this kWh total to what the utility company's meter read and found a discrepancy of about 500 kWh in favor of the utility company. This closely paralleled the additional 10k kWh per year that I could not account for in my projected analysis. Hmmm.... found it! (or so I thought)

So I got on the phone and was soon in touch with the supervisor of the electric meter department. I told him my findings so he and I got together at the client's home one day so that he could test their equipment, which consisted of a transformer/transducer system which reduces the incoming current from the main transformer at the street. After a good hour of testing he informed me that their equipment tested okay. Hmmmm.... bummer.

After many hours of monitoring individual circuits, extrapolating the long-term consumption, I still can't account for this additional 10k kWh per year anomaly. I even looked for hidden conduits coming off the wiring gutter under the transformer, assuming a neighbor might be "borrowing" some power for their growing operation. Nothing. Absolutely nothing.

And now that I've been so thorough with my investigation and extrapolation, I'm left scratching my head, wondering if, even though the utility company tested their equipment as good, perhaps it is not over a long term. I honestly don't know where to go from here... Suggestions?

Tags: accuracy, meter, utility

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Permalink Reply by Tom Delconte on July 25, 2012 at 12:15pm

No one says it better than Wiki.:

Human error has been cited as a cause or contributing factor in disasters and accidents in industries as diverse as nuclear power (e.g., Three Mile Island accident), aviation (see pilot error), space exploration (e.g., Space Shuttle Challenger Disaster), and medicine (see medical error). It is also important to stress that "human error" mechanisms are the same as "human performance" mechanisms; performance later categorized as 'error' is done so in hindsight: therefore actions later termed "human error" are actually part of the ordinary spectrum of human behaviour. The study of absent-mindedness in everyday life provides ample documentation and categorization of such aspects of behavior. While human error is firmly entrenched in the classical approaches to accident investigation and risk assessment, it has no role in newer approaches such as resilience engineering. [so much for resilience engineering!]

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Permalink Reply by peter chang on July 25, 2012 at 1:17pm

Human error would not consistently benefit the perpetrator. That would be called something else. Mistakes that benefit the consumer are less likely to be reported but I've never seen one.
One time my home phone went dead. I checked my records and I was current on payment so I opened my NID and disconnected my house one line at a time, tested for faults, and set them aside. No problems apparent except the lack of signal (dial tone) on the company feed. I went to work. When I got home I could tell someone had been in the yard. I checked for dial tone and there it was, did an ID check and it was my number, so I retested each line and reattached them one at a time. Everything worked fine. My next bill was stunning. They had charged me over $400 for field tech service. I called them up and they told me that the problem had been in my house. I explained the process I had gone through that day and they said they would have to check with the technician and get back to me. At that point I also explained that if thier tech persisted in that the problem was in my home, I would need his name in order to bring charges of breaking and entering since nobody had been at home that day. I was credited on my next bill for the full amount of the service call.

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Permalink Reply by David Williams on July 26, 2012 at 9:27am

Does the home have its' own well?? This can often be wired to the main service entrance which might place it in front of your metering equipment. Look to see if there is a another breaker next the 200 amp main- mine well pump breaker is 40amps. Well pumps and automated lawn irrigation can require a significant load increase an could account for the 25% discrepancy..

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Permalink Reply by Rod Fox on July 26, 2012 at 10:14am

Hmmm...... Well, I asked the homeowner and he verified that there IS a well but it's on a community owned meter. He just gets the pressurized water into his home.

There were a couple of circuits in the main panel that I couldn't identify, but they didn't have any load on them when I isolated them and they certainly weren't any more than 20 amps. I will look in the main disconnect panel though. I haven't yet looked there. But again, I won't be able to do this until after August 8th.

Still waiting on the utility guy to come clean with his monitoring data...

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