TWACS low frequency power line communication signals problematic to public health
The TWACS smart meters communicate with the utility by adding low frequency signals to the electrical lines. Some utilities promote power line carrier (PLC) as a positive alternative to wireless smart meters. The reality is that all PLC technologies are problematic, including the “pulsing” TWACS systems.
The basic facts are that the TWACS system
• creates powerful dirty electricity
• the dirty electricity is a constant presence, possibly 24/7 • the dirty electricity turns all wires throughout the house into antennas • keeping an analog meter will not help enough • the signals cannot be blocked or filtered • scientific studies link dirty electricity with various health effects • some people are hypersensitive to dirty electricity
This article covers all these issues in detail.
The TWACS system TWACS stands for Two-Way Automatic Communication System. It allows the utility company to communicate with smart meters placed on buildings throughout their service area, without having to send out a service technician.
The communication system is two-way, which means the utility can both send instructions to the meter and receive data coming back.
The system can be used to read the electrical usage for a building, instead of sending out a meter reader once a month. The information is typically transmitted a few times a day, but could be only once a month. The transmission may contain information on how much power is used each hour of the day, or even by shorter periods.
Other uses of the TWACS system are to detect power outages, faulty meters, voltage problems, etc. These functionalities will require transmissions throughout the day.
The TWACS system can also be used to remotely control utility equipment such as capacitor banks (Volt and Var Control).
Another possible use is to disconnect the electricity to a household remotely, instead of a service technician having to manually do that on site.
In the future, the TWACS system may also be used for more advanced smart grid functions, such as turning off appliances in people’s homes during energy shortages.
The TWACS system transmits using the existing power lines in an area. It does not use wireless transmissions to communicate with the utility, though it does radiate unintentionally (see later).
The power lines are used to transmit locally between each household and the TWACS receiver at the substation. From the substation, the system communicates with the utility’s central computer using other methods, such as fixed landlines, cell phone modems, microwave links, etc.
The communication speed is very low, placing an effective limit on how many electrical meters it can manage, and how often each meter can communicate. The capacity limits are not publicly available, but this author estimates that a few thousand households per substation is practical, when the system communicates over all three phase wires.
For detailed technical information on TWACS, see the U.S. Patent Office web site(11) and other technical publications.(10, 20)
TWACS can communicate over dozens of miles. It is best suited for rural areas and small towns where houses are further apart than in a city. Rural areas are more difficult to serve with wireless meters due to the limited range of some models.
The TWACS system is marketed by Aclara in the United States, which produces modules that are installed inside meters from other vendors.
Other power line communication There are other systems that communicate via the power lines. These are also problematic, but are not covered in this article.
Any type of system that communicates by transmitting signals via power lines is called a Power Line Carrier or Power Line Communication (PLC) system.
TWACS meters may also be wireless Some TWACS meters also have built-in wireless transmitters. These are currently mostly used to get meter readings from gas and water meters on the house. The electrical meter then passes that information on, using the TWACS system.
On more advanced systems, the TWACS meter may use wireless to transmit signals to a display screen or “smart” appliances inside the house.
The line pulses A TWACS meter sends out a brief pulse about 60 times a second. This pulse travels along the power line to the substation, where it is received. The voltage fluctuations from the pulse may also go in other directions on the local grid, including into other houses in the area, even houses several miles away.
The utility equipment at the substation also transmits by sending pulses on the grid, which it uses to send instructions to the smart meters. These pulses travel on all the local power lines and into all houses. The system would not work if the pulses did not travel to all houses. The pulse does not “know” which meter it is going to, just as the signal from a radio station does not know in advance where the radio receivers are.
For a detailed description of how the TWACS signals travel on the local grid, see appendix D.
A constant stream of pulses A TWACS meter will take about eight seconds(21) to transmit its reading and status, which it may do once a day, a few times a day, or once a month. In between, it may transmit briefer “all is well” messages or other information.
Most of the time, each individual meter does not transmit.
The TWACS controller at the local substation transmits much more frequently, usually several times a minute. It needs to transmit a signal every time a meter is to be read or checked up on (master-slave polling). Some TWACS systems also allow the central controller to download information or programming to the meters.
Together, there is a fairly constant stream of signals on the wires. The signals will be coming from either the smart meter on the building, other smart meters in the area or the controller at the local substation.
With future smart grid technologies, the traffic may increase dramatically.
The substation controller is likely to be the main source of pulses entering the household.
See Appendix B for more detailed discussion of how often the TWACS system transmits.
Powerful pulses The TWACS pulses need to travel for many miles; sometimes dozens of miles. At the other end, the pulse signals must be clearly detectable above the regular line noise, so the pulses must be fairly powerful. The strength of the TWACS transmitters are not disclosed by the vendor, however.
Dirty electricity from TWACS The pulses are more than just a simple pulse. They contain and cause a broad range of frequencies, which are all sent along the wires. The basic TWACS frequencies are in the 400 to 600 Hertz(11) range and are jagged and irregular, unlike the smooth sinusoidal curve of regular power (50 or 60 hertz). These are called transients.
Depending on the physical layout of the local electrical grid, there will also be a wide range of harmonics generated from the basic pulse/transients, as they resonate across the wiring system. The upper harmonic frequencies may reach into the lower kilohertz range.
This is altogether referred to as transients and harmonics. A more descriptive term is dirty electricity.
Dirty electricity from other sources Dirty electricity is created by other sources than the TWACS signals. Many types of household electronics can create them as well, though they tend not to be as powerful.
The power supply inside digital utility meters is a common source of dirty electricity. There are utility meters available with quality components that do not create much dirty electricity, but many meters use components that produce much unnecessary dirty electricity.
Avoiding the high frequency dirty electricity from the internal electronics in a TWACS meter is a reason to opt-out and use a mechanical meter instead, even though it will not help much with the dirty electricity from the low frequency TWACS signals.
The wires become antennas When the broad spectrum of frequencies of the dirty electricity travels along the electrical wires, they are turned into antennas that radiate these frequencies. More precisely, it causes the electrical and magnetic fields around the wires to fluctuate (see Appendix C for details).
The electrical wiring in houses and along the roads are not designed to carry data communication, and are not prevented from acting as unintended antennas.
Cables for telephone, cable TV, DSL and computer systems are intended to carry such transmissions, and are all shielded to prevent the antenna effect.
The wiring in buildings and along the roads will act like giant antennas, similar to what is used for some types of radio transmitters. Decades ago, this principle was used in the Soviet Union to bring AM radio to remote villages. The villagers used ordinary AM radio receivers to play the signals radiated from the power lines going through the area.
The TWACS signals cannot be picked up by AM radios, as different frequencies are used.
Experiments with power line communication, using higher frequencies than TWACS, have resulted in problems with interference with wireless telecommunications. In a paper on the subject by the British Broadcasting Corporation, it was stated:
. . . there is the difficulty for radio-system users that the signals PLT [PLC] injects do not simply travel from point to point along the wiring, they also escape as radiated emissions (emphasis in original).(29)
The industry promoting PLC technology refused to acknowledge any problems existed. Then a research engineer from the British Broadcasting Corporation (BBC) came up with a simple and elegant demonstration of the problem.(28,29)
Such demonstrations resulted in limits being put on PLC systems in Europe and Japan for frequencies that could interfere with telecommunication(10).
The lower frequencies emitted by TWACS do not interfere with telecommunications, but these examples show that power lines carrying communications signals do radiate.
There are also examples of interference from power lines at frequencies much lower than the TWACS signals, such as those serving the electric trains in Sweden.(30)
During World War II, Allied scientists considered using the magnetic field from power lines in Germany as navigational aids for the bombers.(32)
Ground currents Another way dirty electricity can reach humans is via ground currents. Ground currents are electricity unintentionally running in the soil below a house. Like currents running in wires, ground currents will also radiate dirty electricity. Ground currents are a very common phenomenon.
See Appendix A for a more detailed description of ground currents.
Canadian researcher Magda Havas has shown(8) how dirty electricity, riding on ground currents, can be directly measured on the legs of a person.
Low frequencies, but still used for radio transmissions Almost all wireless communication uses frequencies much higher than that emitted from the TWACS system. But some communication systems use frequencies in the same area.
Navigation systems use frequencies down to about 9 kilohertz. The U.S. Navy uses communication systems for submerged submarines in both the 13 kilohertz range and even at 76 hertz — below the TWACS system frequency band.
Coming from “everywhere” There are three ways the TWACS signals can reach into homes:
• from building wiring (electric/magnetic)
• from nearby power line (electric/magnetic)
• from ground currents (magnetic only)
The importance of these three sources varies with the house. Some houses are set well back from the power line along the street, so it is not an issue, for instance.
Some locations have high levels of ground currents, where that may be the dominant issue.
The effects also differ some, depending on where each TWACS signal is sent from (see appendix D).
Cannot be blocked The signals will enter any building connected to the grid, it is not really possible to block them.
Since almost all the signals travelling on the wires are generated elsewhere, it is not enough to put a non-transmitting meter on a building. The signals generated at the substation and some of the other smart meters in the area will continue coming in. (see Appendix D)
There are no filters available to block these low frequency signals. The systems are specifically designed to go right through obstacles, including isolation transformers. Filters that would block the pulse frequencies would also interfere with the normal transfer of electricity. The only place the TWACS signals are stopped is at the substation.(10)
It will not help to turn off the breakers of a home. The breakers disconnect only one wire. It would be necessary to physically disconnect all wires in a circuit (phase, neutral and possibly also ground).
It may be possible to dampen the radiated signals by replacing all household wiring and all cords with shielded cables. Household appliances may also need modifications. This has not been attempted to mitigate TWACS to the knowledge of this author. Also, it will be very expensive, difficult to do correctly, and may not provide a livable solution anyway.
The only viable remedies are to take all or part of the house off the grid, or sell it and relocate to another area. All impose a substantial hardship and are not acceptable solutions.
Typical wireless devices, such as cell phones and Wi-Fi networks transmit from only one point. To limit the radiation, one can go to another part of a house. The transmitters can be placed away from the bedroom to limit radiation exposure during sleep.
The homeowner will have the choice to turn off wireless devices in the home when not in use. There are no such choices with TWACS.
Health studies There have been several studies on whether electricity itself causes health problems. The first study was published in 1979. It is very difficult to study this issue, since there is no control group of people to compare with — no group of people living the American lifestyle, but without electricity. Most health effects also take years to develop — sometimes decades — which also complicates research.
Almost no studies considered whether dirty electricity was present or not, though most lab studies on human cell cultures made sure to eliminate dirty electricity to make sure it didn’t interfere.(22)
Under such circumstances, it is natural that some studies produce conflicting results. It takes more, larger and costlier studies to reach conclusions. However, the World Health Organization has found evidence of a connection between low frequency magnetic fields and cancer.(1)
Research on whether radiation from cell phones and cell towers causes health problems is similarly difficult, again because of a lack of people who are not exposed and many other factors.
Another problem is that much of the research is done by the cell phone industry, which has an interest in showing no effects. There is overwhelming evidence that conflicts of interest do affect the results of research.(2,3,4) A study of cell phone health research found that only 33% of industry-funded research found health effects, while 82% of independently funded research did.(5)
Dirty electricity and health In recent years, researchers have started looking at health effects from dirty electricity.(6)
“Clean” electricity has a smooth, continuous wave of power travelling through the wires. Dirty electricity is not smooth at all, but displays a ragged image of abruptly changing electricity, as seen in the graph on the first page. The radiation from the electrical wires follows the same ragged pattern, which is thought to make dirty electricity less healthy than clean electricity.
The study of health effects from dirty electricity has not become respectable yet, so funding is virtually non-existent, but some interesting studies have been done.
A landmark study took place at the La Quinta Middle School in California, which had a cluster of cancers among the teachers. Some of the classrooms had high levels of dirty electricity and most of the sixteen teachers who had developed cancer taught in those classrooms. The study concluded there was an association with the dirty electricity.(6,7)
Research in Canada has found that dirty electricity appears to make elementary students more disruptive in class and less attentive, and that people with certain types of diabetes have trouble controlling their insulin levels.(6,8)
The International Commission for Electromagnetic Safety (ICEMS) is an association of independent researchers in the field of health effects from electromagnetic radiation. In 2006, 31 scientists from 23 countries issued a statement cautioning against PLC systems.(14)
Dirty electricity creates weak fields, but . . . In most environmental exposures of humans, such as heavy metals, toxic chemicals and noise, it is generally assumed that increasing levels are increasingly harmful.
Electromagnetic radiation is not linear like that. For weak (non-thermal) electromagnetic radiation, it is often the case that weaker fields have a more pronounced biological effect than a stronger field.(13, 22, 23)
In many cases, the weak and precisely tuned EMFs have the most important biological function.(23)
One reason for this seeming paradox may be that small variations can make a big difference(22) and that the combination of frequency, waveform and modulation is of great importance.(13) However, more research is needed to determine the cause.
Dirty electricity is often composed of many weak signals, which in combination may be more biologically active. The TWACS system generates a broad range of frequencies.
Most research studies into biological effects from electromagnetic fields have focused on single frequencies, while few have incorporated modulations, and very few have looked at how several frequencies act together.
Involuntary exposures Risks are a fact of life. The risk of a car accident is accepted in return for being able to reach a destination. Likewise, users of cigarettes and cell phones accept a risk in order to use those products. The user may be more or less informed about the risks, but a choice is made.
The requirement of safety is necessarily higher when a risk is imposed on others involuntarily, when there is no informed consent.
People who are not extremely sensitive to this type of radiation would not notice it directly. Most people would not notice anything at all. Some may get one or more symptoms, such as insomnia, tinnitus (ringing in the ears), headaches or restlessness. These may take some time to develop, making it difficult to know if they are caused by the TWACS systems, as they can have other causes as well.
Electrical hypersensitivity A small subset of the population is particularly sensitive to electromagnetic radiation at very low levels.(16,17,24,25,31) People with electrical hypersensitivity are likely the group most vulnerable to effects from dirty electricity. Some people with this syndrome have had problems with PLC systems(15), and some have had to abandon their homes due to TWACS.(9)
The prevalence of people particularly sensitive to EMF is found by several studies to be about two to five percent of the population, in both Europe and the United States.(18,19,24)
The severity of the illness can vary greatly. A minority of people suffering from this illness are unable to use computers, cell phones, inverters or fluorescent lights, and may even need to live in rural areas to avoid the electrosmog of more populated areas.(17,25)
People with EHS have been shown to be affected by a broad range of frequencies, including both below and above the TWACS frequencies.(31)
The frequencies that are problematic vary with the person, not all people with EHS will react to the same frequencies.(31) As TWACS produces a range of frequencies, it becomes likely that it will be problematic to many people with EHS.
Complicating provocation testing is the fact that some may have delayed reactions, possibly first showing up after the exposure has ended.(25)
It appears that prolonged exposure to specific frequencies may cause sensitization over time, making what is initially tolerable no longer so. This makes ongoing exposures, such as from TWACS, particularly important to avoid.
The illness has only existed since the early 1980s(16), with it first becoming noticed by the U.S. health authorities in the past dozen years. Consequently, it is still poorly understood and still debated. This is normal for an emerging syndrome.(16,25)
The Americans with Disabilities Act (ADA), with amendments, mandates “reasonable accommodations” of people with disabilities, which electrical hypersensitivity is. It should be considered what is reasonable to do for a person who is often on a limited income and who may be unable to continue living in his or her home, due to new technology imposed by a utility. Options include the use of more benign technologies, or technologies allowing a meaningful opt-out, as well as assistance relocating or disconnecting the home from the electrical grid.
Complaints to the utilities At a public meeting in Ridgway, Colorado on November 22, 2011, a local official stated that they had called several other utilities which already had installed TWACS meters. None reported any complaints.
This is not really surprising, and may not mean there are no problems.
Very few people are immediately affected by these systems, that they can tell right away. In a documented case(9) the affected person told this author that he never complained to the utility, as he knew it would do no good anyway. Instead, they simply moved from the area. This sentiment is not unusual among people low on the economic ladder of the American West.
As the symptoms take time to develop and can have other causes, many people would not make the connection, especially if they are not aware that these meters can cause health effects.
The other TWACS meters were electromechanical and didn’t look any different than regular meters, so people couldn’t find out on their own. Some utilities have not informed their ratepayers about the new meters, though many do now. Such information rarely (if ever) includes any information about possible health risks.
Very few doctors are aware of this new phenomenon. New causes of illness often take decades to become generally accepted and communicated to family physicians. It would take a very observant physician to notice an increase in patient complaints and make the connection. The symptoms often take awhile to develop and the meters are usually installed gradually over a year or two, making any uptick in symptoms gradual and difficult to notice.
It would probably take an epidemiologist to notice any effects for a given area. As there is rarely a central database available for these general symptoms, an epidemiologist’s work will be very difficult. Cancers are often centrally registered, but they take many years to develop. As TWACS has only recently been deployed on a grand scale, any possible long term effects have not manifested themselves yet. Consequently, it is unknown whether there will be any.
The few people who do make the connection and do make the effort to complain to their utility may be ignored as cranks. Some who have called or written letters about smart meters in general have been ridiculed and told nobody else had logged a complaint — even though others are known to have done so. It will probably take a dozen or so complainers within a short time period before a utility would notice that there were “any” complaints on such a diffuse issue. Measuring the radiation There are many aspects to electromagnetic radiation, such as the average strength, the peak strength, the frequency, whether it is continuous or pulsed, the modulation, etc. A central issue is whether the radiation is ongoing or is only brief and occasional.
The most common method is to simply measure the average magnetic field strength. For power frequencies (60 Hz in the USA) that is done using a gaussmeter. In this case, it is the equivalent of measuring the average sound level over time of a babbling brook and a gunshot. Over time, these two will produce the same average, but their effects on humans and wildlife are very different.
For continuous and smooth sine waves, that may be sufficient, but the pulsed and broadband waves produced by the TWACS systems are neither continuous nor smooth. The frequencies are also higher, so many gaussmeters may not work correctly.
The dirty electricity creates fluctuations of the regular electrical waves, which makes them more bothersome. As an analogy, one could consider various types of sound. Some people use pleasing sounds to sleep at night. Perhaps sounds of nature, such as waves on a beach. Then imagine replacing this with screeching, disharmonic noise. To a simple sound meter, there is no difference. But to a human, it is very different. A gaussmeter is the same way; it cannot distinguish between clean power and dirty power.
A more appropriate instrument is the Stetzer meter, which measures the voltage fluctuations (dV/dt) and produces a proprietary number, the Graham-Stetzer (GS) unit. The sharp changes in the electrical field are thought to be less biocompatible than the perfect sine wave of “clean” electricity.(6)
However, the Stetzer meter is calibrated for the range of 4 kilohertz to 150 kilohertz, whereas most of the TWACS output is well below 4 kilohertz. This means that the Stetzer meter may significantly underreport the TWACS output.
AM radios are sometimes a useful tool in EMF investigations, but the TWACS frequencies are too low to show up as static in an AM radio.
The best tool for inspecting the TWACS signals is the oscilloscope with a suitable filter to remove the 60 hertz frequency. However, an oscilloscope does not readily produce a specific comparable number. Such an instrument and associated filters also require technical expertise to use correctly. Even better would be a spectrum analyzer, but they are expensive.
Discussion Much circumstantial evidence is available that low levels of magnetic and electromagnetic fields do have biological effects. There is also some evidence that the relative strength of the fields is not the sole standard to gauge by; that frequency, waveform and modulation are also important.
There have been no health studies specifically on TWACS, but a few have been done on dirty electricity. The results of these studies merit caution.
A small subset of the population, the electro hypersensitives, are particularly vulnerable to dirty electricity, sometimes to the point of having to leave their homes.
There is no realistic opt-out method; retaining an analog electrical meter is not a solution. There is also no realistic method to block the signals from coming into a home, other than disconnecting the power. Once the signals are in the house, they will be on every electrical wire, which will radiate out the cocktail of frequencies they carry. The signals are much weaker than a cell phone, but they are present for a large part of the day, perhaps all day and night. The use of the system may be less frequent initially, but is very likely to grow further with time, just as is seen with all other types of networks.
There are better alternatives available for metering technologies today, such as meters communicating through telephone landlines. Most other technologies allow for a meaningful opt-out, while TWACS does not.
It is customary for industry to demand absolute proof of any harm when faced with the threat of regulation. Such a demand may seem reasonable, but absolute proof is a steep requirement. It would require many scientific studies over decades, all financed without a conflict of interest (i.e. without any industry ties). To date, there have been no scientific health studies of these types of systems, and it is unlikely there will be any soon.
Where the public health is concerned, a lower standard is reasonable. It is not reasonable that the cost of any doubt is to be born by the health of the public, especially when the issue involves involuntary exposures, potential long-term health effects and imposing possible major expense. This burden is to disproportionately fall upon a subset of the population which is already disabled and often of limited means.
It is thus not reasonable to wait for absolute proof, especially since such proof will likely take decades to arrive.
Also, the additional cost to the utility of using better technology for new installations, or at least reducing the use of the chosen technology, is relatively modest, possibly zero.
The prudent use of the precautionary principle and simple human compassion should be used to arrive at a reasonable resolution of this matter.
References Articles with a doi reference are available on http://dx.doi.org.
(1) World Health Organization Fact Sheet 193, June 2011.
(2) Scope and Impact of Financial Conflicts of Interest in Biomedical Research, Bekelman et al., Journal of the American Medical Association, January 22/29, 2003.
(3) Doubt is Their Product, David Michaels, Oxford University Press, 2008.
(4) Doubt is Their Product, David Michaels, Scientific American, June 2005.
(5) Source of Funding and Results of Studies of Health Effects of Mobile Phone Use, Huss et al., Environmental Health Perspectives, January 2007.
(6) Dirty Electricity, Samuel Milham, iUniverse, 2010.
(7) A New Electromagnetic Exposure Metric: High Frequency Voltage Transients Associated With Increased Cancer Incidence in Teachers in a California School, Milham and Morgan, American Journal of Industrial Medicine, 51:579-586 (2008).
(8) Dirty Electricity and Electrical Hypersensitivity: Five Case Studies, Havas and Stetzer, World Health Organization Workshop on Electrical Hypersensitivity, October 2004.
(9) Driven Out by PLC, anecdotal story posted on The EI Wellspring website:http://www.eiwellspring.org/smartmeter/DrivenOutByPowerLineSignals.htm
(10) For the Grid and Through the Grid: The Role of Power Line Communications in the Smart Grid, Stefano Galli, Anna Scaglione, Zhifang Wang, Proceedings of the IEEE, June 2011.
(11) United States Patent Office web site contains multiple patents describing TWACS, such as patent number 5933072.
(12) Biological effects from exposure to electromagnetic radiation emitted by cell tower base stations and other antenna arrays, B. Blake Levitt and Henry Lai, Environ Rev 18: 369-395 (2010), doi: 10.1139/A10-018.
(13) BioInitiative Report: A Rationale for a Biologically-based Public Exposure Standard for Electromagnetic Fields (ELF and RF),www.bioinitiative.org, August 2007.
(14) Benvento Resolution 2006, (article 6.6), Electromagnetic Biology and Medicine 25:1970200 (2006), doi: 10.1080/15368370601034003.
(15) Power Line Carrier Communication health effect testimonials, www.eiwellspring.org/smartmeter/PLC_testimony.htm.
(16) Electromagnetic Hypersensitivity, Hviid, Townsend Letter, January 2010, www.townsendletter.com/Jan2010/electromag0110.html. andwww.eiwellspring.org/IntroductionToEHS.htm.
(17) Chemical and Electrical Hypersensitivity – A Sufferer’s Memoir, Jerry Evans, McFarland Publishers, 2010.
(18) Prevalence and risk factors of self-perceived hypersensitivity to electromagnetic fields in California, Patrick Levallois, Environmental Health Perspectives, August 2002 (vol 110, sup 4).
(19) Development and Evaluation of the Electromagnetic Hypersensitivity Questionnaire, Stacy Eltiti et al., Bioelectromagnetics, 28:137-151 (2007).
(20) A TWACS system alarm function for distribution automation, Sioe T. Mak, IEEE Transactions on Power Delivery, Vol 9, No 2, April 1994.
(21) Stated by representatives of San Miguel Power Association at public meeting in Ridgway, Colorado, December 14, 2011.
(22) Effects of Electromagnetic Fields on Molecules and Cells, E. M. Goodman et al., International Review of Cytology, Vol 158, 1995.
(23) Radiofrequency and Extremely Low-Frequency Electromagnetic Field Effects on the Blood-Brain Barrier, Henrietta Nittby, et al., Electromagnetic Biology and Medicine, 27:103-126, 2008.
(24) Disturbance of the immune system by electromagnetic fields — A potentially underlying cause for cellular damage and tissue repair reduction which could lead to disease and impairment, Olle Johansson, Pathophysiology 16 (2009), doi: 10.1016/j.pathophys.2009.03.004.
(25) Electromagnetic hypersensitivity: Fact or fiction, S. J. Genuis, Sci Total Environ (2011), doi: 10.1016/j.scitoenv.2011.11.008.
(26) Ground Currents — An Important Factor in Electromagnetic Exposure, Duane Dahlberg, Concordia College, 1999.
(27) Tracing EMFs in Building Wiring and Grounding, Karl Riley, ELF Magnetic Surveys, 2005.
(28) Demonstration that Power Line Communication turns Electrical Lines Into Antennas. http://www.eiwellspring.org/smartmeter.html
(29) PLT and broadcasting — can they co-exist?, J. H. Stott, British Broadcasting Corporation R&D White Paper WHP 099, November 2004.
(30) Electric trains disturb military installation http://www.eiwellspring.org/technical.html
(31) Electromagnetic Field Sensitivity, W. J. Rea, Journal of Bioelectricity, vol 10 (1&2), 241-256, 1992.
http://www.aehf.com/articles/em_sensitive.html (32) The Invention that Changed the World, Robert Buderi, Touchstone, 1997 (page 174)
Appendix A: Ground Currents The building code in the United States and many other countries requires that the neutral wire of a household electrical system is grounded. This is typically done with a ground rod connected to the main breaker panel for the building.
Nearby buildings will have their own ground rods for their own household wiring.
The transformer will typically also have its own ground rod.
These ground rods are all connected to the same current-carrying electrical system.
Such multiple ground rods may provide an alternative path for the electricity to run down into and through the soil. This is called ground currents or stray currents.
In rural areas, it is common to connect the well casing to the neutral wire as an additional ground rod. This can produce substantial ground currents as well.
In a few rural areas of the United States, the electrical distribution system does not carry a neutral wire. This is called Delta distribution. There are no ground currents in these areas.
In normal household wiring, the phase and neutral wires run alongside each other. Since the currents in the two wires run in opposite directions and they are in such close proximity, their magnetic fields largely cancel each other out.
With ground currents, there is only current in one direction. There is no current running in the opposite direction in the soil. This means that a small current will produce a much larger magnetic field.
Ground currents can be measured by a sensitive gaussmeter. Ambient levels are measured in locations well away from any building and electrical installation, such as in empty lots and parking lots.
Ambient levels in suburbia are typically around 0.1 milligauss, while in rural areas they are around 0.01 milligauss. In open land, they are zero.
Nearer to the source, i.e. inside a house, the ground current radiation can reach a few milligauss.
If the mains are carrying dirty electricity, they will be added to the magnetic field generated by the ground current. The magnetic field will then radiate the frequencies of the dirty electricity. This will not show up on a gauss meter.
Most people would not directly notice these low levels of radiation, but people particularly sensitive can get various symptoms, such as headaches, restlessness and insomnia. Extremely sensitive people may, in a few cases, get more severe neurological symptoms, possibly even seizures.
Dairy cows are well-known to be sensitive to ground currents, which can greatly reduce their milk production.
See (26,27) for additional details and references.
Appendix B: TWACS transmission time and duty cycle The basic TWACS transmission speed is 15 bits per second, as it takes four of the 60 Hertz power cycles to transmit one bit.(20) With encoding, an actual throughput of 100 bps is achieved(10). It takes about 8 seconds to read one meter.(21) Up to six meters can transmit simultaneously(10).
The controller at each substation prompts each meter in turn.(21) Presumably, each of the three phases operate independently, so three meters can transmit in parallel.
The amount of time to read 2000 meters connected to one substation is then:
2000 meters x 8 seconds / 3 phases / 6 parallel = 8.88 seconds . . . or 15 minutes.
This is under optimal conditions. Optimal conditions are rare. Transients on the lines will interfere with the communication, requiring re-transmissions. How frequently this is needed is highly variable.
At a public meeting (21) a utility representative stated that they expected to read their meters in about 30 minutes, once their system was installed. They have 15,000 customers on 8 substations.
Another feature that can generate much network traffic is pinging each meter to check that it is alive and well. This will detect and locate power outages as well as equipment failures.
The equipment at the substation must send a signal (a “ping”) to each meter in turn, and wait for each meter to respond with a brief reply.
The amount of data and time needed for such a transaction is not disclosed, but is here estimated to take 2 seconds.
To ping 2000 meters served by one substation would thus take about
2000 x 2/3 / 6 = 222 seconds = 4 minutes
It costs nothing to do these pings. The more frequently the pings are done, the faster failures are discovered. There is thus much incentive to simply fill unused network capacity with pings. Or at least do it once an hour.
Some meters have the ability to have their software upgraded using the TWACS system. This may happen a few times a year. During such upgrades or programming, the network may be fully loaded for an extended period of time, depending on the size of the upgrade data and whether each meter must be transmitted to individually or the data can be broadcast to all meters of the same model.
With the TWACS basic transfer rate of only 100 bits per second, it will take 10 seconds to transfer 1 kilobyte under optimum conditions. The size of the download will depend on the system.
There are many other features which will add to the overall load of the TWACS system, such as on-demand meter readings, remote disconnect of service, control of capacitor banks, etc. Future technologies, such as smart appliances, can add much additional traffic. The TWACS system is versatile and new technologies are likely to be developed, meaning the traffic can be expected to increase over time.
The TWACS system costs the same to operate whether it is used a lot or very little. This creates an incentive to use the system more than strictly necessary. Essential services, such as a weekly meter read and investigation of reported outages, could be accomplished with little traffic, but a utility is unlikely to agree to that.
The substation controller It appears that the transmissions from the substation controller are likely to be the main source of dirty electricity in a typical household.
This is based on the location of the controller in the electrical system and the fact that it is by far the most frequent transmitter. In this master-slave (or polling) topography, the controller sends a request for each TWACS meter to respond to. The TWACS meters do not initiate communication on their own. The controller is thus responsible for 50% of all transmissions.
The substation controller also provides data downloads to the meters, requests for status, on-demand meter reads, remote connect/disconnect commands, etc. which all adds to the overall traffic.
Simple duty cycle estimate A utility with 2000 meters on a substation chooses to read each meter three times a day. It also chooses to check up on each meter once each hour. A meter reading is considered a check up. The amount of active transmission time is then:
This is for a perfect world, with no transients on the lines causing retransmissions and six meters can always transmit in parallel. Also, no downloads or any other traffic is included.
In a realistic world, there will be many retransmissions and various overhead, making this a busy network, which is essentially transmitting most of the time.
Appendix C: Magnetic and electric fields At the low frequencies of the TWACS system, there are two types of possible effects on humans and animals:
• the magnetic field
• the electrical field
The magnetic field is generated when a current passes through a wire. Whenever electricity is used, there will be a current in the wires feeding the equipment using the electricity. The current goes all the way from the power plant, through the substation, along the distribution lines in the streets and then the wires in the house.
The strength of the magnetic field is proportional to the current. The magnetic field from a cord to a 1000 watt space heater is ten times as strong as the field from a cord to a 100 watt light bulb.
If a wire serves multiple electrical users, their currents add together. A cord serving two 60 watt light bulbs will have twice the current, and twice the magnetic field, of a cord serving only one 60 watt light bulb.
The average magnetic field radiated from electrical wires is measured in milligauss in the United States and microtesla in Europe.
When the current fluctuates, the magnetic field fluctuates as well.
In North America, the AC current always changes 60 times a second. The electricity is delivered with a smooth sine wave form, which generates an equally smoothly changing magnetic field.
When the current also fluctuates with many higher frequencies (transients), the magnetic field is no longer smooth, but appears “ragged” on oscilloscopes. The term is “dirty electricity”.
Dirty electricity is believed by some researchers to be unhealthy. Some people are particularly sensitive to dirty electricity and do not feel well when exposed to it.
Magnetic field disturbance by TWACS meters A household TWACS meter transmits by adding a pulse of current to the line(10), which travels to the substation along the distribution system. This current pulse contains higher frequency signals, in the 400 to 600 Hertz range(11), plus all the higher harmonics which can reach up into the kilohertz range.
Where there are ground currents (see appendix A), the TWACS current can also travel in the soil and reach under the house and sometimes even the neighboring houses.
The electrical field When the substation controller transmits, it sends out voltage pulses, i.e., a spike in the line voltage(10). This voltage spike is designed to reach all TWACS meters in the entire area served by the substation. The TWACS meters all listen for these transmissions, which may prompt them to respond (master-slave).
This means that the voltage spikes, and their higher harmonic frequencies, will travel into all households in the area.
There is an electrical field around every wire connected to the electrical system. This is regardless of whether the wire carries any current or not. An extension cord that is plugged into a wall outlet and nothing else will have an electrical field around it. All the wires inside the walls of a house will have an electrical field around them, even if no electricity is used in the house. The field only disappears if the wires are not connected to the breaker panel.
The electrical field is directly related to the voltage of the wire (relative to the ground). It also depends on how far the wire is above the ground. This is why high-voltage transmission lines are on tall towers compared to the lower poles used for power lines in residential areas.
As the voltage fluctuates, so will the electrical field fluctuate. In North America, the electrical field will fluctuate in lockstep with the 60 cycle (60 Hertz) sine wave AC electricity.
Like the magnetic field, the electrical field will also fluctuate with transients (dirty electricity).
The important difference is that the transients in the voltage will travel on all wires in an area, even those NOT carrying a current. This means that the TWACS voltage transients will reach every wire in every building in the area.
The average electrical field is measured in volt-per-meter (V/m).
The high-frequency voltage fluctuations can sometimes be measured by a Stetzer meter. A better tool is an oscilloscope.
A simple indirect method to show the effects of the electrical field is to connect an AC voltmeter between a ground rod and the hand of a human. The human will act as a receiving antenna.
Appendix D: Sources of fluctuating fields in a home or business The fluctuation of the electrical and magnetic fields of the grid can reach people inside homes and businesses in three ways:
• building wiring
• outside power line
• ground currents (magnetic only)
Which are the most important depends on the local situation.
Some buildings have a power line right outside, while others are set back from the road or sit at the end of the line. Or the line is buried.
Some buildings have poorly constructed wiring, which by themselves create higher fields, making the modulation of greater concern as well. Wiring errors causing elevated fields are common, and most people are not aware of it.
Ground currents exist most places and can be elevated as well, without people knowing it.
The magnetic field from pulse currents The location of each TWACS transmitter is of some importance. The TWACS meter adds its pulse to the current going back to the substation(10). The current pulse does not continue further down the line.
This means that the current pulses from the TWACS meters on buildings will not travel inside a building in most cases.
The current pulses from the TWACS meter (or meters) on the building, and possibly also from a neighboring house, are likely found in the ground currents below or around the house.
The current pulses from meters located further downstream on the power line will pass the house as it rides on the power line back to the substation.
The electrical field from pulse voltage fluctuations The TWACS pulse effects the voltage of the electrical system. The voltage fluctuates just as the current does, but it travels much wider than the current.
These voltage pulses will essentially travel to a home from any TWACS meter and device in the neighborhood, as long as it is connected to the same substation phase line (there are three).
Voltage pulses from the substation controller(10) will reach into every house in the area. This is by intent, so each TWACS meter can listen for instructions.
These voltage fluctuations are an important part of dirty electricity. They make the electrical field inside a house or building fluctuate as well. These fields come from the building wiring and any nearby electrical line along the street.
The following table shows which TWACS transmitter can have which effect on the magnetic and electric fields in a home or building.
Table D.1: Sources and possible effects from TWACS system at a residence or business
This represents our current best estimate, based on the limited technical details available on the TWACS system.
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