EMF Most Frequently Asked Questions


Are there other electromagnetic field sources that are important to know?

Yes. National Electric Code (NEC) wiring violations and shorts can inject ground currents onto metal conduits, water pipes, building steel and HVAC ducts, which can cause electromagnetic interference (EMI) throughout a building.

Are there other RF electromagnetic field sources outside a building that can cause RFI?

Yes. On many roofs and upper floors, antenna farms and microwave dishes can generate RFI (radio frequency interference) and it could exceed potential health and safety electromagnetic radiation (EMR) risks as specified by the 1997 Federal Communication Committee (FCC) Office of Engineering & Technology (OET) Bulletin 65 (Edition 97-01) – Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields. Mandated action (i.e., posting RADHAZ signs, wearing RF personnel alert meters, completion of RF RADHAZ Safety Plan & Training, etc.) is required by the owner/manager of the roof antennas when the electric field strength/SAR levels exceeds the FCC OET Bulletin 65 guidelines for maximum permissible exposure (MPE) for:

  • Occupational/Controlled environments, which applies only to technicians, engineers, maintenance personnel trained to work in elevated/high EMR levels; and,
  • General Population/Uncontrolled environments such as tenant spaces, offices, apartments, hotel rooms, restaurants, and observation decks where people are not aware of potential EMR exposure risks.

If an electromagnetic field problem is discovered at a commercial, institutional or industrial site, can I expect financial help from other sources?

Unless you have specific EMF coverage in your casualty and property insurance, it is not likely you will get financial help from those sources. If you rent or lease space, you can ask the owner to solve the problem or move out. Historically, the power companies have taken no responsibility for electromagnetic field problems. The best course of action is to have a full spectrum EMF survey conducted before you build, buy, rent, lease or renovate any building, area or space. If electromagnetic field problems are discovered, make corrective action mandatory before building or moving in. Prudent casualty and property insurance companies as well as mortgage bankers should survey for electromagnetic fields before offering their services.

If electromagnetic fields cannot be seen, how do you measure levels and source(s)?

Only a qualified EMF engineer, using state-of-the-art instrumentation, can identify electromagnetic field sources and the varying levels throughout a building. Clients should be provided with 3-D color graphical contour plots depicting electromagnetic field levels throughout a room(s) or building plus a written evaluation identifying electromagnetic field sources, recommended mitigation solutions and the costs involved. The written evaluation should also discuss health and electromagnetic field exposure issues, NEC wiring violations and grounding and plumbing current problems — if any.

What are common sources of electromagnetic fields from appliances in the workplace?

What are common sources of EMF’s from commercial building electrical distribution equipment?

What are electromagnetic fields (EMFs) and how will I know if they are present in my building or facility?

Electromagnetic fields are invisible electric and magnetic fields created as a by-product wherever electricity (AC and DC) is utilized. Magnetic fields can penetrate buildings and people and can be detected when computer monitors jiggle or lose color, noise in audio-visual equipment or data errors and loss in magnetic media.

What are some general sources of electromagnetic fields?

What are the most common solutions to electromagnetic field problems?

National Electric Code violations must be found and eliminated (an EMF survey instrument used by a qualified engineer is the quickest way to find shorts). The electromagnetic fields generated by shorts cannot be shielded. As for electromagnetic fields created by plumbing currents, a dielectric coupler will generally solve the problem. If the electromagnetic field source or the affected people and equipment can be moved easily (known as “prudent avoidance”), the creation of empty space (EMFs diminish quickly over distance) could solve the problem. It is very unlikely that productive space will be vacated permanently to solve electromagnetic field problems. Generally, shielding is the most common solution to electromagnetic field problems and shielding the source or shielding the room(s) and people are the two choices. If the electromagnetic field sources are not accessible, then shielding the room(s) or the area in which people work with EMF sensitive equipment is selected — the solution most often used.  See Engineer’s Guide for technical solutions.

What are the most common sources of electromagnetic fields?

AC sources include transformer vaults, network protectors, secondary feeders, switch gears, busway risers, electric panels and transmission lines. DC sources include subways, electrified trains and MRI units found in hospitals.

What criteria should I use to evaluate an electromagnetic field problem-solving solution?

Any electromagnetic field solution should include a written guarantee of performance, i.e. the affected area(s) will not exceed 10 milligauss (the measurement for detecting EMF) at one meter above floor level (average height of computer desks) over 95 percent of the affected area. Generally, 10 mG is the threshold for computer interference. The guarantee should include price, shield design, installation time, final verification report of performance and references. No one shield design cures all electromagnetic field problems. Each shield must be designed to mitigate the particular EMF source(s) and levels present — one shield does not fit all. For example, a steelplate shield will not solve most electromagnetic field problems.