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EMF Testing & Shielding

What are EMFs?

Electromagnetic fields or EMFs are invisible lines of force that surround any electrical device.  EMFs are produced by power lines, electrical wiring, electrical equipment and many other sources.  NRG focuses on EMFs associated with the generation, transmission, and use of electric power.

Electric fields are produced by voltage and increase in strength as the voltage increases.  The electric field strength is measured in units of volts per meter (V/m).  Magnetic fields result from the flow of current through wires or electrical devices and increase in strength as the current increases.  Magnetic fields are measured in units of gauss (G) or tesla (T).  Most electrical equipment has to be turned on, i.e., current must be flowing, for a magnetic field to be produced.  Electric fields, on the other hand, are present even when the equipment is switched off, as long as it remains connected to the source of electric power.  Electric fields are shielded or weakened by materials that conduct electricity, including trees, buildings, and human skin.

Magnetic fields pass through most materials and are therefore more difficult to shield.  Both electric and magnetic fields decrease as the distance from the source increases.  Even though both electric and magnetic fields are present around electrical equipment and power lines, most recent research has focused on potential health effects of magnetic fields.  This is because some epidemiological studies have reported an increased cancer risk associated with estimates of magnetic field exposure.  No similar associations have been reported for electric fields.

Many papers have been written about the health risks associated with EMFs.  Most conclude that there is no significant cancer risk, or problems associated with pregnancy from common levels of exposure to EMFs.  However, electronic devices can be affected, creating a health risk to instruments such as pace makers.

The most common problem associated with EMFs in commercial facilities is interference with computer and other video monitors.  In industrial facilities, NRG has also helped identify and solve problems with production equipment adversely affected by EMFs.

NRG is experienced in identifying and measuring this type of power quality problem, which can be caused or aggravated by unbalanced loads, excessive harmonics and over-loaded or incorrectly run electrical conductors.

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