EMF Measurement Surveys

What factors does an EMF survey evaluate?

EMF is a broad term which can encompass a number of different electromagnetic parameters:

• AC magnetic fields - from power lines, electrical wiring, electrical equipment (more on this below)


• AC electric fields - from power lines, electrical wiring


• RF (radio frequency) fields - from any kind of transmitting equipment, such as cell towers and Wi-Fi routers


• Conducted EMI on the electrical system, commonly called dirty electricity - refers to higher frequency signal components that can be radiated from the electrical wiring in a building

A full spectrum residential EMF survey should evaluate all these parameters. Although there is frequently a single item of particular concern, it is generally wise to check everything. Most problems are amenable to correction (with varying degrees of difficulty), so it's always wise to find out the full scope of what you're confronted with from the outset. A good EMF inspector can advise on remedial measures which have proven effective.

EMF Services no longer performs residential surveys. We are active only in the commercial sector. However, it is often possible to provide a referral to a qualified practitioner in your area. Unfortunately, there are a few companies who make a powerful initial impression, but behind the facade lies a dearth of technical knowledge and an ethical approach that borders on exploitation. You are welcome to call or email and we will help you find a true professional.

AC Magnetic Fields

This rest of this page will focus on the survey of AC magnetic fields from power lines or building electrical systems. If you are interested in an RF survey, that is discussed in great detail on another page of this site: RF Exposure Measurements.

Commercial AC magnetic field (EMF) surveys are usually conducted for one of these reasons:

• Site assessment of an open tract to evaluate the impact of power lines and to provide guidance in the placement of new construction. We have particular expertise in the survey of power line EMF. Our automated sampling equipment will collect detailed data at defined intervals across a plot of land, and produce graphic output which is precisely distance correlated. Other instruments on the market will perform logging, but their graphic output is time correlated rather than distance correlated, so the recorded magnetic field cannot be referenced to specific points. EMF Services uses top quality professional equipment that is maintained within the recommended calibration cycle to ensure a high degree of confidence in the results.

• Evaluation of a commercial space where equipment is being adversely affected by building electrical systems or other interference (EMI) sources, or where concern about human exposure exists. An analysis of electrical wiring and grounding systems from the standpoint of field production is an essential part of a comprehensive building measurement survey. The information derived from this analysis forms the basis for our remediation recommendations. The experience gained from hundreds of surveys over the years is an important part of the professional product that we deliver.

EMF Survey Reports

The fully documented reports that we furnish our clients are an important part of each survey, and provide a point of reference for understanding the significance of measurement data. Each report references applicable exposure standards, precautionary exposure guidelines, and equipment interference thresholds. Also included are full prescriptive recommendations for correction of any anomalous conditions. The ultimate goal of our surveys is to place you in a position to make a responsible and informed decision about the area under evaluation, and to understand the options available for field remediation.

Survey Report Graphics

Plot of AC Magnetic Field near a Power Line

Mapped Magnetic Field Survey of an Office

7 Day Log of Magnetic Field Levels near a Power Transmission Line

Multiple Measurement Paths across a Plot Under Evaluation