Radio Frequency FAQ

What is "radio frequency"?
Radio waves and microwaves emitted by transmitting antennas are one form of electromagnetic energy. They are collectively referred to as ‘radiofrequency’ or ‘RF’ energy. RF is used in many products that most people interact with as part of modern daily life, such as cellphones, wireless laptops, radios, televisions, pagers, cordless telephones, microwave ovens, baby monitors, garage-door openers and walkie-talkies.

How is RF related to SmartMeter™ technology?
SmartMeters™ utilize a low power (1 watt) wireless radio to send customer energy-usage information wirelessly to PG&E for data collection. This innovation enables customers to better manage their energy consumption, because they have data that was not previously available to them.

At what frequency in the electromagnetic spectrum do PG&E’s SmartMeters™ operate?
PG&E’s electric SmartMeters™ operate in the 902-928 MHz frequency-band to communicate customer electricity-usage to PG&E. PG&E’s gas SmartMeters™ operate in the 450-470 MHz frequency-band to communicate customer gas-usage to PG&E.

Do electric SmartMeters™ constantly emit RF?
No. SmartMeters™ communicate intermittently, with each RF-signal typically lasting from 2 to 20 milliseconds. These intermittent signals total, on average, 45 seconds per day. For the other 23 hours and 59 minutes of the day, the meter is not transmitting any RF.
I use a cell phone every day. How does the RF from a cell phone compare to the RF from an electric SmartMeter™?
The RF from an electric SmartMeter™ is roughly one one-thousandth that of a typical cellphone. In fact, you’d have to have one of our meters on your home or business for more than 1,000 years to get as much exposure to radio waves as a typical cell phone user gets in just one month.

What is RF exposure based on?
Exposure is based on the transmitter’s power and your distance from the source. The chart below reflects SmartMeter™ transmitter power and the "power density" (i.e., RF-exposure) at 1 foot from the meter.
  Frequency
(MHz)
Transmitter
Power (watts)
Power Density (µW/cm2) at 1 foot away FCC Safety Standard
(µW/cm2)
Gas SmartMeter™ 450-470 0.820 0.00166 300
Electric SmartMeter™ 902-928 1 8.8 601

In general, doubling your distance cuts the "power density" by a factor of four. That’s why at a distance of 10 feet the radio waves from an electric SmartMeter™ are only about one one-thousandth as much as a typical cell phone.

What levels of RF will an electric SmartMeter™ add to the environment?
The meters will add signals that are similar to those produced by 900 MHz cordless phones and wireless routers commonly used within homes for distributing Internet to various computers. Because the transmitter output powers are so low, and because the signal level decreases substantially with greater distance from a meter, the overall aggregate RF field levels that would be expected to be found in a neighborhood with SmartMeters™ will remain very low (whether compared to pre-existing RF fields in a neighborhood or government-health-protection standards for RF fields).

How often does the electric SmartMeter™ send RF signals and how does being inside the home effect exposure?
A meter may send or receive several signals of between 2 to 20 milliseconds each day (sometimes referred to as "chirping"), but the number of signals during a day depends on several factors, including the position of a meter in the mesh network. Since the average transmission time for an electric meter is 45 seconds (total) during a 24-hour period, the exposure will be 45 seconds. However, because the Federal Communications Commission’s standard for RF-exposure considers not just RF-signal strength and the duration of the signal, but also distance, one needs to consider that any distance between the SmartMeter™ and the person, and the intervening presence of the house-wall and the back plate of the meter, will significantly reduce the strength of the RF-signal.

Government-Regulation of RF and Safety Concerns

Who regulates RF?
The federal government, particularly the Federal Communications Commission (FCC), has exclusive jurisdiction over RF.

Are SmartMeters™ safe?
Both the federal government and the international community have deemed the low-level RF on which PG&E’s SmartMeters™ rely to be completely safe.

In 1996-97, the Federal Communications Commission (FCC) established a standard for what it calls "Maximum Permissible Exposure" (MPE), i.e., what level of RF-exposure is safe. With input from the Food and Drug Administration (FDA), the Environmental Protection Agency (EPA), and other federal government agencies, it established the following safety standards:

  • In the 902-928 MHz band (at which PG&E’s electric SmartMeters™ operate), average exposure of less than 601 microwatts per square-centimeter (µW/cm2) per 30-minute-period. PG&E’s SmartMeters™ are only 8.8 (at one foot away).
  • In the 450-470 MHz band (at which PG&E’s gas SmartMeters™ operate), average exposure of less than 300 microwatts per square-centimeter (µW/cm2) per 30-minute-period. PG&E’s SmartMeters™ are only 0.00166 (at one foot away).

SmartMeters™ are also safe by international standards. The International Commission on Non-Ionizing Radiation Protection (ICNIRP) has set its standard for this frequency at approximately 450 µW/cm2, more than 50 times greater than an electric SmartMeter™.

The World Health Organization (WHO) and many other health agencies confirm that there is no persuasive evidence that low level RF exposure (such as those on which SmartMeters™ rely) cause any adverse health effects.

What is the "Bioinitiative Report" and what are the limits set by European standards organizations?
Preliminarily, it is important to note that PG&E’s SmartMeter™ equipment complies by many orders of magnitude with both the applicable federal standard that the FCC has issued, but also with international standards. Whereas the RF-exposure at 1 foot away from a PG&E electric SmartMeter™ is 8.8 microwatts per square-centimeter, the FCC has set its safety threshold at 601 µW/cm^2 and the International Commission on Non-Ionizing Radiation Protection (ICNIRP) has set its standard for this frequency at approximately 450 µW/cm^2. In either case, PG&E’s SmartMeters™ release a mere fraction of what the federal government and international community have deemed safe exposures.

PG&E is aware of the BioInitiative Report. PG&E also is aware of the vast criticism the BioInitiative Report has received within the scientific community. The consensus of the scientific community is that the BioInitiative Report is un-objective, self-selected research. It does not represent the consensus of the international scientific community regarding safe RF exposure, as reflected in the 2009 Technical Information Statement released by the Committee on Man and Radiation ("COMAR"), a technical committee of the Engineering in Medicine and Biology Society ("EMBS") of the Institute of Electrical and Electronics Engineers ("IEEE"):

"The focus of this COMAR Technical Information Statement is to identify quality sources of scientific information on potential health risks from exposure to RF energy. This Statement provides readers with references to expert reports and other reliable sources of information about this topic, most of which are available on the Internet. This report summarizes the conclusions from several major reports and comments on the markedly different conclusions in the BioInitiative Report (abbreviated BIR below). Since appearing on the Internet in August 2007, the BIR has received much media attention but, more recently, has been criticized by several health organizations (see Section titled "Views of health agencies about BIR"). COMAR concludes that the weight of scientific evidence in the RF bioeffects literature does not support the safety limits recommended by the BioInitiative group. For this reason, COMAR recommends that public health officials continue to base their policies on RF safety limits recommended by established and sanctioned international organizations such as the Institute of Electrical and Electronics Engineers International Committee on Electromagnetic Safety and the International Commission on Non-Ionizing Radiation Protection, which is formally related to the World Health Organization." (Emphasis added.)

The IEEE is just one organization that has criticized the BioInitiative Report and instead followed the safety recommendations of the WHO and ICNIRP. The following reflect still more criticism of the BioInitiative Report:

What is the peak power output from an electric SmartMeter™ and why does PG&E’s report use average power density?
It is important to note that the maximum power of the radio in a SmartMeter™ is only one watt.

In an August 6, 2010 letter from Julius Knapp, the Chief of the FCC’s Office of Engineering and Technology, to Cindy Sage, the FCC advised that it is the average power, not the peak power, of a device that is relevant for exposure evaluation.

"Since the purpose of these devices is to provide very infrequent information they transmit in occasional bursts. Thus, for exposure purposes the relevant power is maximum time-averaged power that takes into account the burst nature of transmission, and based on the typical time-averaged transmitter power for many of these devices, they would generally be compliant with the local [specific absorption rate] limit even if held directly against the body." [emphasis added]

Notwithstanding the FCC’s view that peak transmissions are not the relevant measure of RF for purposes of evaluating exposure, it is important to note that the RF from electric SmartMeters™ is very weak and very brief. PG&E’s independent evaluator found that the time-averaged power density at one foot from the meter is 8.8 µW/cm^2 (microwatts per square centimeter) when you conservatively assume a 4-percent duty cycle (a duty cycle is defined as the percentage of time the radio is in an ‘active state,’ or transmitting) , and is well within the FCC exposure limits for time-averaged power density, which is 601 microwatts per square-centimeter. But this very conservative calculation results in an overstatement of the time-averaged power density number, as a 4-percent duty cycle is equal to nearly one hour (57 minutes) of transmission time per day, when the actual transmission time for an electric SmartMeter™ is on average less than one minute per day (45 seconds). If you adjust the calculations for the actual duty cycle, the RF from PG&E’s electric SmartMeters™ is considerably lower.

What happens if multiple meters are located together on the same building, and will this increase the RF signal strength when they send at the same time?
Although it is theoretically possible that two SmartMeters™ in close proximity could transmit at the same time, the very short duration of each signal means that there is little opportunity for overlap and therefore the signals from the meters can be regarded as essentially independent. The signal from an electric SmartMeter™ typically lasts between 2 to 20 milliseconds and the cumulative signaling during a day would typically total, on average, 45 seconds.

The FCC recently wrote in detail on this subject, specifically about SmartMeters™, and stated as follows:

"With respect to multiple adjacent Smart Meter installations, since the antennas for each device are mounted individually on each utility meter, the separation distance from most people for most of the transmitting antennas is relatively large compared to 20 cm and the meters’ contributions to the total potential exposure at any location are small, as only the nearest few transmitters can add meaningfully to the total. Further, as a practical design matter, when several of these meters are placed in a cluster, they have to communicate with a single controller. In order to ensure that the controller receives the information properly, only one transmitter can communicate with the controller at a time, eliminating the potential for exposure to multiple signals at the same time. ...

In addition, the exponential decrease in signal strength over distance and additional signal losses due to non line-of-sight conditions for distant sources ensures that only the contributions of nearby transmitters are significant. ...

Irrespective of duty cycle, based on the practical separation distance and the need for orderly communications among several devices, even multiple units or ‘banks’ of meters in the same location will be compliant with the public exposure limits." [emphasis added]

Are there potential interference problems from SmartMeters™ for people with pacemakers?
The FCC concludes the following about interference with pacemakers from radio frequency signals:

"The FDA requires pacemaker manufacturers to test their devices for susceptibility to electromagnetic interference (EMI) over a wide range of frequencies and to submit the results as a prerequisite for market approval. Electromagnetic shielding has been incorporated into the design of modern pacemakers to prevent RF signals from interfering with the electronic circuitry in the pacemaker. The potential for the "leads" of pacemakers to be susceptible to RF radiation has also been of some concern, but this does not appear to be a serious problem." (FCC Office of Engineering & Technology Bulletin 56: "Questions and Answers About Biological Effects and Potential Hazards of Radiofrequency Electromagnetic Fields" (Fourth Edition, August 1999)

The US Food and Drug Administration (FDA) provides similarly on its website:

"Radiofrequency energy (RF) from cell phones can interact with some electronic devices. This type of interference is called electromagnetic interference (EMI). For this reason, FDA helped develop a detailed test method to measure EMI of implanted cardiac pacemakers and defibrillators from cell phones. This test method is now part of a standard sponsored by the Association for the Advancement of Medical Instrumentation (AAMI). This standard will allow manufacturers to ensure that cardiac pacemakers and defibrillators are safe from cell phone EMI."

The FDA’s website continues on to add that "based on current research, cell phones would not seem to pose a significant health problem for the vast majority of pacemaker wearers."

While all of the foregoing applies to cell phones, SmartMeters™ have two fundamental differences: First, the SmartMeter™ is attached to a house or business and cannot, without great difficulty and a clear intention to do so, be placed next to a person’s chest (i.e., closer than a few inches to the meter’s antenna, which is contained within the metal and plastic of the meter, and thus already a distance from someone nearby). Second, the strength of the signal from a SmartMeter™ diminishes very rapidly with distance, so the inability to carry the meter in your pocket, coupled with an individual’s distance from the meter, limits one’s RF-exposure. It also is worth noting that SmartMeters™ only communicate intermittently for between 2 and 20 milliseconds at a time, totaling on average approximately 45 seconds per day, so the weak RF fields that SmartMeters™ utilize are further limited by time.

Currently, medical device manufacturers advise patients to consult with their physicians when a patient has concerns about RF devices and interference. Although devices like SmartMeters™ have a typical RF exposure that is weak, distant, and extremely brief, PG&E would nevertheless advise any customer with concerns related to a medical device to consult with his or her physician for personal medical advice to best address his or her concern.

RF From Other Sources

How do SmartMeter™ RF signals compare to other common devices?

Examples of RF in the Everyday Environment Compared to SmartMeter™

Power Density in Microwatts per square centimeter (µW/cm2)
Adjacent to a gas SmartMeter™ (1 foot) 0.00166
Adjacent to an electric SmartMeter™ (10 feet) 0.1
Adjacent to an electric SmartMeter™ (1 foot) 8.8
Microwave oven nearby (1 meter) 10
Wi-Fi wireless routers, laptop computers, cyber cafes, etc., maximum (~1 meter for laptops, 2 - 5 meters for access points) 10 - 20
Cell phones (at head) 30 - 10,000
Walkie-Talkies (at head) 500 - 42,000
Source: Richard Tell Associates, Inc.

Interference Between SmartMeter™ and Other RF-Products

Do SmartMeter™ RF-signals interfere with electronics and other wireless devices?
Generally, no; millions of smart meters are in operation at both PG&E and other utilities and there have been few incidences of interference.

What are the federal regulations that address radio interference?
The FCC CR 47 Part 15 regulations limit RF emissions for all electronic and radio equipment and there are additional FCC rules for radios that operate in "shared" frequencies. PG&E's SmartMeters™ use a shared frequency and are certified that they meet all relevant FCC requirements.

Why are there any cases?
Even FCC compliant devices operating in shared frequencies may be affected by other devices operating in the same shared frequency band. The FCC shared frequency rules are essentially "good neighbor" requirements limiting when, how often, and how strong transmissions may be. However, even with these limits sharing a frequency band has some impact on each device performance. Each equipment manufacture makes design choices so their device is less likely to affect or be affected by other products in the same FCC compliant neighbor bans.

Why is interference so uncommon?
Most vendors design their products such that the impact of neighbor devices has no noticeable effect on their product performance. Also, PG&E SmartMeters™ on average transmit radio signals less than a minute per day and at low radio signal strength levels.

If you are a customer and you believe that a device in your residence is interfering with a SmartMeter™, please contact us at 1-866-743-0263.

Can other devices that use RF signals to operate interfere with SmartMeter™ communication?
We have reviewed the potential for interference from other devices and have not seen any evidence of jumps or dips in SmartMeter™ data and/or readings. It is noteworthy, though, that SmartMeters™ use the wireless information only to communicate the collected readings/data, not to measure usage. As a result, even if the nearby devices interfered with the SmartMeter™ communication, it would only slightly delay the communication of the read values, and would not interfere with the values themselves. This is much the same as if interference blocked a mobile or cordless telephone transmission. Once the interference is gone, the message can still be communicated accurately.
 

Additional RF Resources

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