In reviewing an electric utility industry document from 2010, it is quite clear that the industry knew of safety and accuracy issues with smart meters before they were ever manufactured and deployed.  The title of the document is “Accuracy of Digital Electricity Meters,” published by the Electric Power Research Institute (EPRI).

What is so incredible about the document is how strongly it was acknowledged that traditional analog meters were “an amazing of piece of engineering work.”

Quoting the EPRI document:

“By anyone’s assessment, traditional electromechanical meters are an amazing piece of engineering work.  Refined over a hundred years, the design of a standard residential electricity meter became an im­pressive combination of economy, accuracy, durability, and simplic­ity.”

“Most don’t likely recall their electricity meter ever failing.  Such is the reliable legacy of the electromechanical meter.”

On the subject of accuracy for analog meters:  “Although simple and mechanical, the result was like a vault, locking-in and protecting the reading of cumulative consumption and immune to sudden shift or loss of data.”

On the subjects of both safety and accuracy:  Electromechanical meters are “generally immune to standard surge events.”

Why Change from Analog Meters to Digital Meters? 

With traditional meters being so impressive, safe, and reliable, why would anyone change to something else?  Were digital meters somehow superior in any technological manner?  No, they were not.  It is a shame we could not have stuck with the old adage that, “if it ain’t broke, don’t fix it.”

As indicated in the EPRI document, the change was driven by a desire for additional “functionality.”  The utilities wanted a more economical means to charge consumers with “time of use and real time prices”:

“Manufacturers who designed the first solid state residential meters understood the challenge they faced.  The electromechanical devices they intended to replace held the trust of both utilities and the general public.”

“Electromechanical meters are dependable products that have served society well.  Over a hundred years, their design was optimized so that they provided an excellent combination of simplicity and reli­ability while providing a single measurement – cumulative energy consumption.  Unfortunately, these products did not support the additional functionality needed to integrate customers with a smart grid, such as time of use and real time prices, a range of measured quantities, communication capability, and others.”

“New meters may enable new rate structures such as time-of-use or critical peak pricing.”

“The impetus that finally drove the transition to solid state metering was not cost reduction, nor improvements in service life or reliability, but the need for more advanced functionality.  Electromechanical me­ters, with that familiar spinning disk, did a fine job of measuring total energy consumption, but became extremely complex if required to do anything more.  Versions that captured peak demand and versions that measured consumption in multiple time-of-use (TOU) registers have existed, but were not economical for residential purposes.”

Digital Utility Meters Have “Voltage Transient Susceptibility”

Although the EPRI document was ostensibly written about meter “accuracy,” it reveals a fundamental safety weakness with regard to all digital meters (as compared with analog meters) in a section entitled, “Voltage Transient Susceptibility.”  Quoting the document:

“The electronic circuits of solid state meters connect to the AC line to draw operating power and to perform voltage measurement. …  A range of electronic clamping and filtering com­ponents are used to protect the electronics from these voltage surges, but these components have limitations.  The ANSI C12.1 metering standard specifies the magnitude and number of surges that meters must tolerate. …  In any case, surges that exceed the tested limits, either in quantity or magnitude, could cause meter damage or failure.”

“Electromechanical meters had no digital circuitry.  They utilized spark-gaps to control the location of arc-over and to dissipate the energy of typical voltage events.  As a result, they were generally immune to standard surge events.  This nature is evidenced in the section of ANSI C12.1 that specifies voltage surge testing, but al­lows that ‘This test may be omitted for electromechanical meters and registers’.”

Based upon the above information, it should not be surprising to see recent reports in the news of “exploding smart meters” following power surges and that these types of incidents do not normally occur when dealing with the more “reliable legacy” electromechanical meters.  For example:

To more fully explain the safety issue, as indicated by EPRI, surge events can cause a digital meter failure.  When that failure occurs catastrophically,  an explosion or fire may (and sometimes does) result.  Analog meters are generally immune to such failures.  

Embedded Software and Sensitive Circuitry Can Result in “Glitches”

The EPRI document also reveals how the utilities and manufacturers knew that “glitches” and “transient glitches” could result from the use of meters using digital circuitry.  These glitches would affect the accuracy of meters, and the transient glitches might be quite difficult to troubleshoot, as shown below:

“Solid state electronic meters are designed to provide [the] same register function [as analog meters], but using embedded software and non-volatile memory chips as the storage mechanism.”

“There is the possibility of imperfections in the embedded software or sensitivities in the electronic circuitry.  Hypothetically, such imperfections or sensitivities could result in glitches that could affect the meter reading.”

“With electromechanical meters, modes of failure tend to be perma­nent.  Once a meter or its register fails, due to wear, dust, etc, it is generally still found to be in a failed state when tested later.  Software flaws, on the other hand, could create a transient glitch, leaving a meter that checks-out perfectly afterwards.  This possibility compli­cates the diagnostic process for solid state meters and may make it difficult to discern the root cause of problems.”

Summary and Analysis

As stated by EPRI, “electromechanical meters are dependable products that have served society well.”  The utility industry’s transition to digital meters inherently exposes the consumer to a number of risks.  Meter accuracy and safety are two of those risks as delineated in this article.  There are many more, including invasion of privacy, health, and cyber security threats to name a few and which have been discussed in other articles at this website.

The EPRI document on accuracy concludes by mentioning:

“there will likely be both real and perceived issues with solid-state designs that need addressing.  Care must be taken to consider each case thoroughly and to use sound diagnostic practices to trace each issue to its root cause.”

“Ideally, each inves­tigation should not only resolve any homeowner concerns, but also discover any product imperfections so that solid-state meter designs may be continually improved.”

Editor’s Note:  In other words, regarding the above quotes, consumers will be used as guinea pigs for unproved digital meter designs.

Summerland Failed MetersThe EPRI document’s final sentence states:

“When advanced metering functions are needed, reverting to electromechanical meters is not a viable option.”

So with the acknowledged inherent design issues with digital meters, reverting back to the old reliable analog meter is not considered “a viable option.”  This conclusion is basically the result of a straw man argument followed by careless and  narrow-minded people wanting to promote the manufacture and sale of smart meters.

The argument for “added functionality” centers around the perceived need by utilities to charge customers time of use and real time prices.  This in itself is a debatable topic, but even in the EPRI document it was mentioned that electromechanical meters have been designed with time-of-use (TOU) registers, but they were not considered “economical for residential purposes.”

In addition, as recently stated by the Executive Director for the New York State Smart Grid Consortium, “AMI is not needed to send price signals through the grid.”

Furthermore, we have previously pointed out that the smart meter is a canard and reflects a diversion of resources from where money should actually be spent to build a truly resilient electric grid system.

With the ongoing troubling revelations about digital utility meters, we need to more strongly challenge the straw man argument that there is no viable alternative to the analog meter and that an alternative is even needed.  In fact, the analog meter has been shown to be technologically superior in terms of performing the required function of delivering electric service to customers in a safe, reliable, and economical manner.  Let’s stick with what we have unless a truly superior meter can be demonstrated to take its place which meets the necessary functionality requirements.  Otherwise, our health and safety are unnecessarily put at risk.  In addition, billions of dollars will continue to be wasted if smart meter deployments persist.

Primary Source Material for this Article

“Accuracy of Digital Electricity Meters,” Electric Power Research Institute (EPRI) White Paper, May 2010, available through the following link:
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