The first type is surveys for health reasons, and the second is for equipment placement for optimal function or the prevention of electronic malfunction.
Health reasons for testing can be quite varied. These may range from testing for site compatibility for an employee's pacemaker or defibrillator to determine if it will function throughout the day without suffering interference issues ranging to several employees claiming that the work environment is causing or has caused their illness.
A medical device manufacturer will have extensively stress-tested their products for EMI immunity before going to market, ensuring their relative safety. Nevertheless, severe electromagnetic environmental stress will cause any electronic to fail. The patient's doctor can make EMI threshold levels of a biomedical device available, then you can call on Elexana to test your facility.
Site testing is usually rigorous. Pacemakers and other biomedical implants require specific certified calibrated equipment. The surveyor needs an OSHA certification, has experience working in industrial sites, and his/her company must have General Liability and Professional Liability Insurance.
The health effects from regular and frequent exposure to substantial radiation levels for the surveyor can be considerable. An experienced surveyor knows how to measure to reduce his/her exposure, but often, because of the high levels it takes to cause interference to a device and the elevated levels in some facilities, over-exposure cannot always be avoided.
If an employee is complaining about the EMI or EMF levels at the workplace, this is a somewhat different situation for the EMF Consultant. Often, we see that the employee has a meter purchased on the internet and finds that their measurements exceed those standards related to specific standards.
There are many problems with these types of measurements. First, these meters are usually uncalibrated and skew readings towards an exaggerated high side. Also, inexpensive meters made for amateurs are prone to spurs or internal circuitry overload and often present false peak readings to the high side. Another measuring technique mistake that I even see "professionals" doing is to place a meter too close to the source. We have all seen the amateur put the RF meter to the cell phone or wifi or a Trifield EMF meter to an electrical panel. (It is one thing to do this for a photo-op, but another for a survey.)
Most meters cannot measure in the extreme of the near-field. Indeed, no RF meters can measure in the near-field accurately. A third mistake I see amateurs, and some "professionals" make is that they do not identify the correct energy source; instead, they measure the correct energy but identify the wrong energy cause.
Perhaps, this digression is for another posting?
So, there are surveys that measure from a source point, and then the typical industrial surveys measure on a grid or a straight line. Often, a factory will have support columns marking each section. These marked sections make it easy to document a grid survey. Sometimes, a GPS enhances the measuring and documentation process. Other times, using our NFA 1000s, we can data log and map simultaneously. (See the chart.) (Note: Calibration of the NFA1000 takes place in Germany.)
Grid surveys can be helpful. Upon identifying elevated levels, add an overlap survey to determine the correct sources and proper mitigation.
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