EMI and EMF Site Surveys

ELEXANA provides EMI and EMF Testing, Analysis, Troubleshooting, Advanced Data Logging, Surveys, Assessments, and Mitigation Consulting.

ISO 17025-certified, calibrated instruments for all high-risk measurements, assured accuracy, and replicability, with traceable official reports. Our EMI/EMF survey measurements include GPS coordinates and time stamps.

Why Be Concerned About EMI?

Electromagnetic interference (EMI) causes latency, malfunction, and sluggish performance to fine electronics such as computers, medical devices and equipment, pacemakers, financial trading platforms, graphic software, recording equipment, etc.

With the exponential increase of wireless technologies in New York City, EMI has become a common vernacular. Line noise, harmonic transients, dirty electricity, RFI (radio frequency interference), and electromagnetic coupling are synonyms.

How Do You Know It’s EMI?

An easy way to tell if you have an EMI issue is to look for the presence of:

Unwanted screen images, patterns, static, or artifacts.
Overheating of any metal enclosures. Are enclosures very hot to the touch?
Motor failures from overheating.
Fuses blowing for no apparent reason.
Static or interference on sound or voice communication.
Electronic equipment shutting down for no apparent reason.
The computer malfunctions or locks up.
Flickering of fluorescent or LED lights.
Blinking incandescent lights.

Electromagnetic energy coupled to circuitry and components causes electromagnetic interference (EMI).

The Four Types of Electromagnetic Coupling

1. Conductive Coupling occurs when the coupling path between the source and the receptor forms direct electrical contact with a conducting body,

An example of Conductive Coupling occurs when a municipal water service pipe has a reverse neutral stray current, and the lightning protection system ground wire connected to it conducts this neutral current back onto the neutral bus of an electrical panel. Line EMI or signal-to-noise can occur from the same or opposite directions.

We call this common impedance when the signal-to-noise ratio appears in phase in the same direction on both conductors.
We call this differential impedance when the signal-to-noise ratio appears out of phase, in the opposite direction on both conductors.

2. Inductive Coupling occurs when a strong electromotive force intersects an electrical conductor within a magnetic field, causing the original magnetic field to become distorted. James Clerk Maxwell, who preceded Albert Einstein, mathematically described this process as "Faraday's Law of Induction." An example of inductive coupling is when an underground power line runs close enough to a water pipe that the pipe acquires leakage current.

3. Capacitive Coupling occurs when two fluctuating electrical fields co-exist between two adjacent conductors, thereby inducing a change in voltage on the receiving conductor receptor. Capacitive Coupling is among the most intriguing and challenging for the new student. We see this occurring when we turn off the branch circuit in a room and register that the electric field has become stronger. This happens because the electrician had strung wires in parallel from different branch circuits.

4. Radiative Coupling occurs when the distance exceeds one wavelength between the source point and the receptor. The source point emits or radiates an electromotive force across space that a conductor receives. An example is a cell transmitter sending signals that inadvertently couple onto your equipment’s wiring. This is termed “unintentional coupling.”

Welding equipment can stress pacemaker function.

EMF/EMI Surveys fall into two categories; these need to be defined.

1. Surveys for health reasons, or 2. Equipment placement to optimize function; analyzing an environment to prevent or solve equipment malfunction.

The human exposure reasons for testing can 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, to employees claiming that their work environment is causing them harm, 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 device 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 should be rigorous and thorough. Pacemakers and other biomedical implants require specific, certified, calibrated equipment. The surveyor needs an OSHA certification and must have experience working in industrial sites. The company must carry General Liability and Professional Liability Insurance.

If an employee complains about the EMI or EMF levels at the workplace, the situation is somewhat different for the EMF Consultant. Often, we see that the employee has purchased a meter on the internet and finds that their measurements exceed the specific standards. However, there are many problems with these types of employee 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, often presenting false peak readings to the high side. Another mistake I see "professionals" make in measuring technique is placing 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 be measured at the extreme of the near field. Indeed, no RF meters can be measured accurately in the near field. 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.

So, surveys are measured from a source point, and typical industrial surveys are measured 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. After identifying elevated levels, an overlap survey will be added to determine the correct sources and proper mitigation.

EMI Services

Equipment Interference Issues and Concerns: On-site EMI troubleshooting, diagnostics, and attenuation for laboratory and medical equipment, metal detectors, surveillance equipment, autonomous vehicles, trading platforms, broadcast, video, and music recording
Industrial EMI diagnostics and analysis for AIC - Artificial Intelligence Compatibility™
Research laboratory EMI diagnostics and analysis for SEM/TEM on-site electromagnetic compliance to specifications
Medical laboratory EMI diagnostics and analysis for MRI, NMR, EKG, and EEG equipment on-site compliance
Electromagnetic interference (EMI) attenuation for peak electronic, computer performance, and information technology equipment
RFI, E-Field, B-Field, GIC, H-Field, and AC magnetic shielding design
Architectural and engineering EMI/RFI consultations
EMC/EMI Pre-Compliance testing at your facility
Long-term data logging and RF masking