Photograph of an electric meter too close to a bed and sleeping area - high EMF will be measured if quite close to electrical meters EMF Survey Errors: Local Indoor & Site Sources of EMF Affect Site EMF Surveys

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This article describes the identification & measurement of local outdoor or indoor EMF electromagnetic field sources as part of a recommended procedure for performing electromagnetic field (EMF) or electro-magnetic radiation EMR measurements in gauss or milligauss.

We discusses sources of error and variation in EMF measurements and we review and make suggestions for using several low-cost EMF measurement devices to determine the instantaneous electromagnetic field exposure.

We describe the identification & measurement of local outdoor or indoor EMF electromagnetic field sources as part of a recommended procedure for performing electromagnetic field (EMF) or electro-magnetic radiation EMR measurements in gauss or milligauss.

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Other sources of electromagnetic fields may be greater than a power transmission line, may confuse readings, and might in some cases deserve attention.

Electrical appliances toaster coffee maker (C) Daniel FriedmanElectrical appliances commonly found in buildings (TV's, toasters, clocks, microwave ovens, electric motors), generate their own electrical fields, in some cases pretty strong ones.

However remember that the field strength falls off as the square of the distance from the source.

And remember that an appliance generates a field when it's electrically active or "turned on."

So unless your toaster is running 24-hours a day, and unless you're sleeping with your head next to the toaster, the fact that it generates an electrical field (while you're making toast) is, from an EMF health exposure view, pretty unimportant.

We conclude that power-company funded studies which focus attention on home appliances are simply funding a red herring to distract already-frightened consumers, but we also emphasize that in most cases the fear that some people have about EMF exposure is not appropriate and that other more dangerous hazards may be present.

Electrical service entry mast head and cable (C) Daniel FriedmanBut having investigated a number of interesting cases and complaints, we have found cases where specific items in buildings were creating a strong and constant electromagnetic field.

Occupants who wish to take the EPA's advice of "prudent avoidance" (that means avoid without going to extreme measures and without panic), might use their new EMF meter to look at the following cases:


  • An electrical service entry cable (SEC) running down the outside of a home happened to be on a wall against which, inside, an infant's bed headboard was placed.

    The distance separating the infant's head from the SEC was thus only about 10", and at the pillow I found a very strong EMF. Solution for prudent avoidance: move the bed away from this building wall to a different location.

Moving even three or four feet away from this line usually reduces the measurable EMF field strength from the electrical service entry cable to below the range of detection.

we have found exceptions to that rule where metal building piping or steel beams (or in one case sewer piping) appear to carry EMF to other locations more distant from the source.

Photograph of an electric meter too close to a bed and sleeping area - high EMF will be measured if quite close to electrical meters

  • A bedroom had been built on a converted porch. The SEC and electric meter were enclosed in a wooden "box" and chaseway which was right next to the bed's headboard.

    EMF measurements and solution were the same as for the case above.

  • Steel piping carrying electrical fields from other locations in a building: In an basement apartment of a large building I found very strong EMF measurements near the ceilings of the apartment.

    I observed that steel building water pipes ran close and parallel to a large bank of 24 electrical meters serving the building. Apparently the electrical fields at the SEC wiring and meters were being picked up and transmitted across the building by its plumbing.

  • Steel sewer piping carrying electrical fields: At a suburban community local road which was crossed by a high voltage power transmission line, I found that the entire street appeared to generate a strong EMF.

    We observed that the street contained a large buried steel sewer line that appeared to conduct the EMF away from and at right angles to the power line. There was no measurable effect from the street's field at the nearby homes themselves.

  • A home's aluminum siding appeared to be showing a strong EMF. I found that improper electrical wiring, including a defective clothes dryer and improper grounding of the electrical system was causing some of the siding to actually carry current when the dryer was operating.

  • Other safety hazards may much more dangerous than EMFs: a final and really important example: while measuring EMF's at properties, or while performing other types of environmental inspections, I have often found sever immediate hazards such as unsafe chimneys, boilers without relief valves, combustible gas leaks, or dangerous electrical or fire hazards. It would be foolish to become so focused on an concern for electromagnetic fields (EMF) that one failed to notice immediate and severe threats to life and safety.

Some studies by some experts have suggested a possible link between exposure to electromagnetic fields and various cancers or other health problems. Other studies suggest that no definite correlation could be demonstrated. It is likely that the jury will be out on this matter for some time, for both economic and political reasons.

Our photo shows an uncommon exposure to an electrical field: the electrical meter and service entry cable produce a field which can be detected up to perhaps two to four feet away. But the history of construction at a building can bring surprises.

An outside porch first enclosed this electrical meter; later the porch was enclosed and converted to a bedroom. Our model shows that someone sleeping on the side of the bed next to the electrical meter was likely to be sleeping in an EMF that could easily have been avoided: move the bed to an opposite wall.

Small absolute health risk from EMF: Most researchers indicate that where a risk is present, the absolute risk level from EMF is likely to be small, and less than other less obscure hazards. (Automobile accidents, trip and fall, fire, and shock hazards, smoking and other health risks.) Consumers should not let focus on a specific emotionally-charged hazard distract them from these other more mundane but more dangerous concerns.

Often but not always, the relative strength of such fields falls off in much shorter distance than that from power transmission facilities. However in some instances where occupants wish to maintain prudent avoidance, it is possible to make a significant reduction in exposure by small changes in arrangement of devices or locations of working or sleeping areas.


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EMF LOCAL SOURCES MAY EXCEED POWER LINE STRENGTH at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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