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Measuring EMF in Your Home
Many a story are told about Electromagnetic Fields (EMFs) causing havoc in ones house. People get ill, possibly cancer and other devastating ailments, including electrosensitivity. Wi-Fi networks, cell tower electrosmog, dirty electricity, ground currents, and power lines are common offenders. Note that house inspections do not include EMF measurements of any sort. It's therefore prudent to make an effort and be aware of the EMF measurements in your habitat.
A particular concern is the wild proliferation of smart meters, which produce dirty electricity and emit radio frequencies.
Common measurements include the magnetic field, electric field and Radio Frequency (RF). Meters can be obtained from various stores on the web such as LessEmf. It is recommended that one gets a low frequency meter to measure magnetic and electric fields (such as the "Trifield Meter EX100") and an RF meter to measure high frequency non-ionizing radiation (such as the "Gigahertz Solutions HF35C").
For more professional meters there are the "Gigahertz Solutions ME3030B" or "Gigahertz Solutions ME3851A" combination meters, and for Extended Range of RF Frequencies there is the "Gigahertz Solutions HF35EC". The "Acoustimeter" has a very wide frequency band and is easy to use.
One can also use a special meter to measure dirty electricity, such as the "Stetzer Meter" or an Entech Powerline Noise Analyzer, and don't forget the handy AM radio, which can detect a broad range of very weak magnetic fields up to a maybe a mega hertz. The MFJ-856 Line Noise Meter with a 3 Element Beam is very sensitive. At 135 Mhz it picks up frequencies beyond the capability of a cheap AM radio, though the narrow bandwidth limits it's capability. Its large direction antenna is very useful for identifying sources of noise.
EMF guidelines provided by the FCC are based on short-term thermal effects. One has to literally be cooked before their limits kick in. In fact, their criteria is based on the rise in temperature of a rats ass after being microwaved for a few minutes. For instance, the current permissible level of non-ionized radiation is on the order of 1000 uw/cm2! More realistic exposure limits for the severely electrosensitive are approximately:
AC Electric Field: 1 v/m
AC Magnetic Field: 0.05 milli gauss
RF: 0.02 uw/cm2
A Close Look at Electricity
These are just rough estimates and true tolerances depend on the frequencies and their modulation.
Here we explore electrical power in the home. It's instructive to inspect electricity because the house consists of a matrix of wires throughout the walls and ceilings. Most of the time we sleep next to walls filled with wires. Also, devices or appliances, especially TVs and computers are particularly a nuisance to electrosensitives.
If a computer affects a person twenty or more feet away, many assume it's the result of dirty electricity. In today's age more and more devices are producing noise on our lines. Take for instance compact fluorescent lamps that some idiots use instead of the incandescent (Edison) light bulb. Also, new devices, from routers to cell phones are now exclusively powered or charged with switching mode supplies, which produce high frequency noise. Our environment is rapidly changing, and we can't rely on Uncle Sam to see to it that these devices are not detrimental to our health.
The discussion begins with a look at the noise in a house's electrical lines. Then we raise the noise up a notch and create much dirtier power. The techniques used to measure the power require special equipment and circuits rather than a simple meter.
First is a bird's eye view of relatively clean house voltage as seen on an oscilloscope. This pic, and the following others, are produced by first filtering out the prevalent 60 Hz using a high-pass filter. House Power - Base Level The prevalent low frequency waves, at a few hundred Hz, are a bit exaggerated because of resonance in the filter, while the higher frequency noise is relatively low. Here is a closer look at the mid-high frequency noise at 30k Hz House Power Base (30k Hz). The peak to peak voltage is about 50 milli volts. Here's a close look at one mega Hz noise, House Power Base (1M Hz). The magnitude is also about 50 milli volts.
Now have a look after it's been polluted with Halogen lighting. Dirty House Electricity This view was produced by turning on halogen track lighting on the same circuit being analyzed. The noise is now clearly visible. Here are views at higher frequencies Dirty House Power (30k Hz) Dirty House Power (1 M Hz) The 30k Hz noise is staggering when seen up close. Though, there's no significant increase in 1M Hz noise. The halogen lamps are 12 volts, each with a very noisy switching power module.
It seems to be common knowledge that computer power supplies contribute to dirty power. The depictions here somewhat downplay such theories, at least for this L2000 HP laptop computer. Here is the power with a laptop computer running from its AC power adapter, Computer Power (30k Hz), Computer Power (1 M Hz).
At 30k Hz the magnitude of the noise has not increase significantly to the house electricity, however one can observe that the 30k Hz waves are more distinct. The 1 M Hz noise is hard to see, however, the magnitude is actually less than the house electricity without the computer on. Though there is more of a digitized look, which means there are higher frequencies involved. One can dispute whether the noise produced by the computer is significant to cause biological affects. Though the noise is measureable and clearly visible.
TVs can be a serious nuisance to sensitive people even as far as 30 feet away. Here's a look to see whether a TV in a condo next door can pollute electricity. This is a condo's (fairly clean) electricity with the TV off, TV Off (30k Hz), and then with the TV on TV On (30k Hz). There's a very subtle difference and it's not reproducible. This means most of the electrosmog from the TV is radiating rather than conducting over the wires. Lastly, here's a pic of the power filtered with a shunt capacitor TV Off Filtered It's nice and clean with the 1 mega hz common mode noise nearly non-existent. Without the filter it had a amplitude of 0.15 volts, and caused the fuzzy affect.
As we have seen with the Low Emission Computer ambient measurements (just a few feet away) can be negligible yet the computer can still cause devastating symptoms much further away. This TV is similar in that meters at hand are unable to detect the emitted EMF at a distance. The electrosensitive person is vulnerable to neighbor's electropollution, particularly when living in a condominium or apartment.
A low-pass filter can be very effective in reducing dirty power. For instance here is pic of the cleansed electricity with those same halogen track lights on, Filterd Power Halogen Lights On (30k Hz) What was 3 volts peak to peak is now less than 0.25 volts. Lastly, is a pic of the power to the computer after it is filtered by the low-pass filter, Filterd Computer Power (30k Hz). The cleanliness of the electricity proves that the filter works under load.
Differential noise on a house wire can be reduced with a shunt capacitor. A 20 uF capacitor plugged into a receptacle can serve this purpose. Mind you that these capacitors only reduce mid frequencies from the line, in the 30 kHz range, which happens to be exactly where switching supplies run. From a personal experience such filters offer little relief from electosensitive symptoms caused by electomagnetic pollution emitted by TVs or computers. The 120 volt Panasonic capacitors that were used produce a high pitched noise which causes ear irritation, but that was solved by placing a 1.0 ohm resistor in series with the capacitor. The resistor slightly compromises the effectiveness of the capacitor. Others who suffer from Hyperacusis also experience discomfort with the leading brand of such filters.
Since the capacitor doesn't offer very much relief from TVs, it may be concluded that much of the EMF is being irradiated or still being conducted through the house wiring and of course the signal on the coaxial line. Be aware that shunt capacitors only reduce differential noise between the hot and neutral lines, but not common mode noise. The prevalence of interference detected by an AM radio on lines filtered by shunt capacitors suggests that common mode noise is prevalent and should not be ignored. It should also be noted that when a capacitor is employed near a device that produced dirty electricity, the measured differential noise may be low at that outlet, however elevated differential noise can then be measured at other outlets! Differential noise is converted to common mode noise back to differential. Proponents of the capacitor filters insist that one needs 20 or so units distributed throughout the house, making such a solution borderline farcical. Depending on a shunt capacitor as a filter is like buying a car that can only make right hand turns.
Filters designed to reduce both common and differential mode noise are available, but require a good ground. True filters have inductors, which literally trap high frequencies. Such filters can be placed between the house receptacle and say a computer if one wishes to provide cleaner power to the device and prevent dirt from traveling back onto the house lines. Here's one that you plug right into the receptacle, CORD CONNECTED FILTER). A good ground is not the ground available in the receptacle outlet, but rather an independent line, more than likely connected to a stake grounded to earth. The receptacle ground can be used as a last resort, but if the ground wires are ganged your going to have a mess on your hands due to stray currents running through your house. The filter concepts filter just mentioned only filters a device on that particular receptacle. If your electricity is dirty from the power company then most likely you'll need a filter placed upstream perhaps at the fuse panel. For a hefty price, a military-grade filter can be placed outside if one is concerned about filtering power prior to it entering the house, which makes the installation less convenient than shunt capacitors or the filter concepts, which are simply plugged into outlets.
Linear Power Supplies
A linear power supply is a cleaner alternative to switching mode. Noise still emanates from the diodes as they switch on and off. Diode noise can be reduced when a capacitor is placed across the diodes of the bridge rectifier. Here is a pic of a linear "wall wort" with the capacitors soldered in place. The tiny power conditioning capacitor is being replaced with a much larger one, which reduces ripples in the output voltage. This same wall wort is used to power a low EMF home-brew linear battery charger. Most battery chargers on the market produce immense amounts of dirty electricity.
Satellite TV service introduces high frequency EMF pollution into homes. The switching mode "power inserter" which powers the dish is extremely noisy. Furthermore the noise gets onto the coaxial cables which are fished throughout the house. To make things worse, DirectTV requires that the dish and set top boxes to be powered all the time. One can remediate these issues by replacing the power inserter with a linear one, and place the set top boxes near the dish. Then use a fiber optic HDMI cable to transmit the video to the TV. Even though the noise on the coaxial cables are low voltage, the long cable is an antenna. The same can be said for long runs of Ethernet cable, which can also be replaced with fiber at a relatively reasonable cost.
We've all heard about dirty electricity, however this brief study brings the topic in new light. Rather than using meters, one has a chance to literally see what electricity looks like in their home. It can be revealing how some appliances, such as those low voltage halogen lights, can produce potentially dangerous levels of dirty electricity. Filtering was shown to be effective in reducing high frequency noise. Such filters can be used to filter the power used by computers or other appliances. Ideally one would cleans the house by eliminating EMF spewing devices altogether.