Know Your EMI Tolerance and EMF Safety Levels Before Hiring an EMF Testing Company

You could need EMI Compliance or EMF Safety tests for all sorts of reasons. Before you jump into the internet search rabbit hole, do some homework based on your needs. 

If you need to know if a new piece of equipment will function properly at a new location, then check the manual for EMI tolerance specs. We even had one piece of equipment that required a specific meter be used for the compliance test, or the manufacturer’s guarantee would not be applicable.

If you have a medical device, such as an anesthesia table, then know that there is a specific FDA compliance testing procedure that this little side table must undergo. Be sure that during your manufacturing process, you put the table under the rigors of pre-compliance testing to save you time and money.

Are you interested in RF emissions from an industrial dryer that emits 27-30 MHz of strong RF, then you need to know National IEEE, OSHA, and your particular state’s DEP safety regulations. We recommend also knowing international standards for occupational safety. If one day you wish to partner with a Chinese, Israeli, or European firm, then they may insist that their workers are operating within their own country’s guidelines.

If you wish to buy a new investment property, then you need to not only know the US safety levels, but you also need to know all of the international safety standards. A European or Israeli company is often not concerned with the US safety levels because the standards are so much lower than the rest of the world’s standards. For example, the US safety level for exposure to AC Magnetic Fields is 1,000 mG (milligauss) whereas the Israeli safety level is only 4 mG. Another example; the US/IEEE safety level for radio frequency exposure is 10,000,000 µW/m² whereas much of the world’s safety level including Israel, Germany, France, Russia, and China’s is 10,000 µW/m². Salzburg, Austria’s and Luxembourg’s limits are 1,000 µW/m².

If you wish to have your family residence tested, then you should do some research to know what AC Magnetic, AC Electric, and RF emission levels are acceptable to you. Elexana’s safety limits for residential work are in line with the Building Biology® Institute. We are certified Electromagnetic Radiation Specialists (EMRS). 

Be sure that the EMF Company you are interviewing shares with you their EMF Safety Actionable Levels long before you hire them. If they believe that 10 mG is an acceptable level and 10 mG is what their shielding will leak, then any electron microscopes or scanners will be situated within a magnetic environment that may not meet manufacturer’s specifications.

Wiring error identification is a service that a trained and certified EMRS learns how to provide. It does NOT require an electrical license because it is non-invasive. Wall outlet receptacles or electrical panels do not need opening up to provide this service. 

Every trained EMRS works with an electrician who will then do the follow-up work. We can instruct an electrician on how to troubleshoot and identify problems in a mains or a sub-panel. Our affiliate licensed electricians continue the process we begin, making your home safe from potential electrical fires and AC Magnetic Fields, created by wiring errors, which can cause a possible fire. Often, we see that a more efficient electrical system will lower your monthly utility bill.  

Hand-Held Radio Frequency Meters: Pros vs. Cons

Pros:

Hand-held RF meters are cost-effective and easy to use. Those with a logarithmic periodic antenna are particularly good at identifying general source points, such as smart meters, cellular antenna ports and towers, wifi, cordless phones, BlueTooth, etc. For this reason, the Gigahertz Solutions HF59B and HF59D hand-held meters serve well the excellent work that an Electromagnetic Radiation Specialist, EMRS, provides you. 

The Gigahertz Solutions HF59B, one of the best hand-held RF analyzers (Made in Germany), is most responsive in the ‘Sensitive” setting and measures RF signal power to a resolution of a microwatt per square meter (µW/㎡) for power readings. Unfortunately, it does not take much to overload this setting, so the max settings that bump the measurement units up to a milliwatt per square meter (mW/㎡) are often required. It has a running RMS (Root-Mean-Squared Average) setting and a PEAK and PEAK-hold function that do not average but sum the three highest received peak frequencies. By the FCC, this mathematical method is acceptable as a viable calculation method.

The isotropic antenna (Isotropic is a “donut-shaped” pattern above the antenna) has a typical zero dBi (decibel-isotropic) gain. This means the measurements are relatively linear (consistently representative of the actual signal strength across all frequency bands) and do not require antenna factor calculations. (The logarithmic periodic antennas and all other log-per antennas require compensation calculations because the dipole antennas that make up a log-per antenna resonate with specific frequencies more than others. So, these resonating frequencies will be received better than others. The weaker resonating frequencies will be received as a weaker signal than in reality, so compensation for the signal as measured weaker than it is are needed for those specific frequencies. This compensation is termed the antenna factor, AF.)

Cons:

The typical hand-held meter is a scalar measuring instrument that can exaggerate the measured power density levels. It can also under-measure.

A Gigahertz Solutions RF Analyzer and most hand-held meters can under-record a cell tower measurement. Today’s 5G antenna ports emit five different frequency bands. So, if the analyzer is only summing three of the highest amplitudes, it will not account for the two bands with weaker signals. (The effect of RF on electronics and persons results from power density and other factors such as frequency, phase modulation, pulse amplitude variations, and distortion.)

In addition, because these meters cannot measure phase, any impedance mismatches and reflections can add in and out-of-phase distortion with the incident signal you are measuring, resulting in magnitude uncertainty. This typically occurs while measuring inside any room or on a New York City block because of multiple reflective surfaces. An EMRS is aware of this issue while measuring indoors and tries to account for this during the assessment.

Most hand-held RF meters are broadband and not frequency selective. As a result, all unwanted signals caused by the meter’s circuitry will get averaged into the measurement, often causing false or inaccurate readings. This is why we throw out spike readings that do not correspond to a smart meter’s demodulated audio signal.

Intermodulation resultants are signals generated by nonlinear interactions within the transmitter components. For example, the internal mixer which processes the RF signal has a nonlinear behavior. The mixer outputs the sum and difference of three input signal frequencies via diode sensors, and then the output is isolated. Most high-end meters have an IF Filter (Intermediary Frequency Filter.) The higher frequency summation is a process known as up-conversion, meaning that the output frequency is higher than the second input frequency.

The problem with using any mixer within the circuitry path is that mixers can present signal combinations along with their harmonics and leakage of the input signals to the output. The frequency and amplitude of the intermodulation resultants will then change with a delta in the input signals, resulting in yet another way to get an incorrect measurement. Care and experience can minimize this effect in specific environments, but it is nearly impossible to avoid in a dense RF environment such as New York City.

We term any unwanted signal as a spurious event or spur. Spurs from internal circuitry leakage and external radiative coupling may occur at any frequency or power level. If you use any hand-held RF meter or hand-held spectrum analyzer, there is a good chance that your peak readings will have spurs. Therefore, we recommend monitoring the RMS (root-mean-squared) readings, taking extended-time measurements, and voiding any one-time spike readings.

Often, you can use your own eyes to locate RF sources unless you are in a big city or a rural area with dense foliage and do not have an FCC mapping of licensed antennas in your vicinity. Generally, a hand-held RF meter is not the correct tool to acquire data for scientific assessments of RF signals, except for a specific few makes and models. Still, meters such as the Gigahertz Solutions HF59B and HF59D will work for general residential work where you want to get a sense of the relative power levels entering your space.

Usually, if you want accurate isotropic broadband measurements for scientific purposes, then either ascertain an isotropic broadband antenna with a dedicated spectrum analyzer or find a hand-held meter that isolates the antenna from the electronics, has internal RF shielding with a built-in attenuator, and monitor the RF signals for a longer time-span.

Calibration and Professional Meters:

A professional meter, for most applications it is designed for, has an up-to-date ISO 17025 calibration certificate. This certification includes a detailed report of the +/- decibel (dB) error or percentage level of uncertainty for each frequency and measurement traceability to a specific up-to-date calibrated tool.

If the meter has a NIST (National Institute of Standards) traceable certification only, then it is helpful as a reference tool but not for taking critical high-risk measurements such as for the aviation industry, industrial safety, pacemakers, etc.

If your meter has a factory calibration, measurements are generally certified by the manufacturer at their stated accuracy for one year. Most measuring equipment used frequently will go out of calibration within one year.

Up-to-date calibration certificates should be included in your report. If you are a professional providing high-risk assessments, we recommend you use ISO 17025 certified-calibrated equipment.

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Grounded vs. Ungrounded Electrical Devices

Please note: All persons using power tools on a new site should always use a power cord that has a GFCI, Ground Fault Circuit Interrupter. Outlet testers will not necessarily inform you if you are protected from a possible lethal shock.

This article pertains to equipment and electronics that are powered by either a battery or AC electrical power using a power cord that contains an internal ground wire connected to its third-prong grounding conductor pin. This ground conductor wire, which should actually be termed a bonding wire, inside the power cord is then bonded to some part of the equipment’s metal casing and connects to the ground conductor in the electrical wall outlet and then continues onto the ground bus bar in the electrical mains panel and ultimately to the Earth ground (soil) using a ground rod, ground grid, etc.

Any ungrounded device, termed “floating, that is plugged into a wall outlet receptacle is a possible shock hazard if shorted. Floating devices will also emit a 6-8 foot electric field (in theory, emanating to infinity) from their power cord and from the powered device itself, even when the device’s power switch is in the off position.

While standing within a 6-8 foot radius of any ungrounded electrical device (the reactive near-field), the corresponding E-Field emitted by this “floating” ungrounded device and its cord will couple onto any metallic objects within this radius. This coupling includes any metal enclosures, metal structures, and your epidermis. The closer proximity any of these conductive objects are to electrically floating equipment, the higher the capacitively coupled voltage will be to the receptor, you, also electrically termed the “victim.” 

Depending on the resistance of your skin’s natural insulators (usually between 1,000-100,000 ohms differing from one person to another) and the voltage frequency, your resistance to any nearby voltage will vary. However, common to all of us is that our natural insulation begins to break down once its frequency exceeds 1.7 kHz (Applied Bioelectricity, From Electrical Stimulation to Electropathology, by J. Patrick Reilly, Ph.D., MIT, Johns Hopkins University.)

Battery-powered devices emit DC electric fields. Devices that use an electrical cord emit AC electric fields. Most people do not know that DC static electricity can have a more interruptive effect on electrical equipment than an AC electric field. Anyone who uses an oscilloscope will eventually learn this fact, hopefully not the hard way.

If a third-pronged power cord is plugged into a wall outlet with “open” ground, meaning the ground conductor is not connected (wired incorrectly,) that tool is considered electrically floating.

(Please, do NOT bend a ground pin so that your tool can plug into an ungrounded receptacle. And, again, always use an outlet tester to verify if the ground tail is connected.)

We occasionally find homes and offices with unconnected grounding ground tails, so it’s always good to have your electrician check that these are connected properly to avoid potential shock from a short circuit. While you are at it, check that your GFCIs (Ground fault Circuit Interrupters) are functioning correctly, too. You can easily find an outlet tested that has this function. Here is a good one: Sperry GFI6302 GFCI Outlet/Receptacle Tester

Please, know that an outlet tester will only inform you if the ground conductor is connected to the outlet receptacle via a mechanical ground. It will not indicate whether your electrical safety system EGC, Equipment Ground Conductor, is functioning correctly. You also need to be sure that your circuit breakers are in good working order. We recommend yearly electrical inspections by your licensed electrician and that you maintain all of your electrical equipment and panels. 

Schedule an annual checkup of your EGC, Equipment Ground Conductor, the Overcurrent Protection System, and all GFCIs. Elexana LLC can conduct these checks. Generally, electricians do not have the tools to measure ground resistance/impedance. Hopefully, someday, this will change.

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