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EMF Electric Fields – Design Consulting

by / Friday, 24 October 2014 / Published in Green Building Consulting
Visualize Electric Fields

EMF Electric Fields

EMF design consulting for human-generated electrosmog should involve Radio Frequency (RF) radiation, dirty electricity (high-voltage transients), low-frequency magnetic fields, and low-frequency electric fields. These four elements can be wrapped under the umbrella term, “electromagnetic radiation,” or “EMR.” This blog focuses on basic practices to minimize low-frequency EMF electric fields during design and construction. This summary of electric field design guidelines is part 2 in a 4-part series.

AC EMF only exists in the “extremely low frequency” (ELF) and “low-frequency” (LF) portion of the ElectroMagnetic Spectrum. In this lower-frequency bandwidth we can distinguish between electric fields and magnetic fields.

ElectroMagnetic Spectrum EMF Electric Fields

ElectroMagnetic Spectrum EMF Electric Fields

Most EMF consultants in the US have been trained and certified through the International Institute of Building Biology & Ecology (IBE). They offer an entry-level 5-day seminar that is over the heads of most folks without any electrical engineering or electrical installation experience. They also offer more advanced trainings and focus on minimizing exposure around sleeping areas. Some of the following diagrams come from IBE. There are a few EMF experts in the US that have not gone through the Building Biology trainings.

Measuring EMF Electric Fields

Measuring EMF Electric Fields

Electric Fields – How to measure, and how much is too much?

When performing EMF surveys many “EMF consultants” only evaluate low-frequency magnetic fields.  When folks call and say they “have an EMF meter” and are measuring “high emf,” they generally have a Gauss meter and are measuring magnetic field field strength or magnetic flux. Most Building Biologists focus on Alternating Current (AC) electromagnetic fields, and in addition to magnetic fields we evaluate low-frequency electric fields. Building Biologists place low-frequency electric and magnetic fields under the umbrella term “electromagnetic fields,” or “EMF.”  In higher-frequency radiation the electric and magnetic fields cannot be measured separately, but in low-frequency radiation we can distinguish between electric and magnetic fields. They behave differently and are measured in different units.

Electric fields can easily be detected using a voltage detector. These nifty and affordable gadgets can tell you if you have a live wire, and more sensitive voltage detectors can also alert you to ambient electric fields if the field strength is high enough. EMF electric fields can also be directly measured and data logged with an ambient electric field meter, like the NFA1000, or measured indirectly with a specially calibrated multimeter via “Body Voltage Testing.” Body voltage testing originated in Germany and remains a suitable way to measure relative impacts of surrounding electric fields. Healthy Building Science uses both methods for EMF testing.

Electric Field Allowable Limits

Electric Field Allowable Limits

Ambient electric fields are measured in Volts per meter (V/m). Body voltage (indirect electric field) readings are in millivolts (mV). Building Biologists would prefer electric fields below 0.3 V/m or 10 mV in sleeping areas, but most accept anything up to 1.5 V/m or 100 mV as an acceptable target for sleeping areas. It is not uncommon to find initial readings well above these conservative targets. But don’t panic. Our industry groups will save us! Perhaps not surprisingly, the Building Biology targets for sleeping areas are WAY below the American Council of Governmental Industrial Hygienists (ACGIH) recommended exposure limits.

Building Biology Limits for Electric Fields

Building Biology Recommended Precautionary Limits for Electric Fields

What are Low-Frequency Electric Fields?

Electric fields are present whenever voltage is present. Voltage is “electrical potential,” and is independent of current flow (amperage).  EMF electric fields are present even if a device is not on. Electric fields emendate from any “live” electrical cord or energized wire. If one could visualize electric fields they would look more like lightening bolts, hair, or spaghetti – emanating from a live source – and,  for lack of a better term, “finding the path of least resistance to ground.” Because of this natural “attraction to ground,” it makes shielding electric fields relatively easy.

If you were to stand barefoot under a power line you would become like lightening rod for electric fields. Some artists have visually illustrated EMF electric fields by jamming tube lights into the earth beneath power lines. They will light up!

Visualize Electric Fields

Visualize Electric Fields

Electric fields are very unlike magnetic fields, which are only present when there is amperage (current flow). And magnetic fields are shaped more like donuts which get predictably less intense further from the source. Shielding magnetic fields is much more challenging.

Common Point Sources for EMF Electric Fields

  • lamp or clock radio cords
  • extension cords
  • in-wall wiring and outlets (plugs)
  • overhead light fixtures
  • computers and other electronics
  • power lines

Electric Field Design Consulting

When starting from scratch there are many easy opportunities to minimize electric field exposure. This is a sample of items we generally include in healthy wiring guidelines:

  • distance and wiring layout
  • MC Cable (metal clad wiring) around sleeping and high-use areas
  • demand Switch or “Kill” Switch
EMF Mitigation - Electric Fields

EMF Mitigation – Electric Fields

Electric Field Shielding – EMF Mitigation

Minimizing electric field exposure in existing buildings is much easier than mitigating magnetic fields. Most commercial buildings are wired using metal clad wiring so electric fields are shielded and relatively low. However, here’s a sampling of relatively easy ways to minimize electric field exposure in existing homes:

  • distance from live wires and appliances (unplug bedside light, extension cord, etc.). As long as a device is plugged in it has voltage (electric fields) to the switch.
  • shield between known sources (usually wiring) and high-use areas. There are special fabrics, meshes, and paints for the job. Electric field shielding must be grounded.
  • shield electric cords for appliances and extension cords.
  • install and automatic or remote control demand switches to turn off circuits around high-use areas.

For more information about electric field consulting please visit our other EMF blogs, check out our EMF testing page, or give us a ring.

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