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Wiring Error Investigation

Wiring errors, sometimes even seemingly minor ones, can create “Net-Current” conditions which can cause elevated magnetic fields over a large area.

(Typical magnetic fields from a transformer vault, for example, fall off relatively quickly with distance, however, these fields do not.)

When a building’s wiring is installed according to Code (National Electric Code), current goes out and returns on the same circuit path, maximizing the natural cancellation of magnetic fields from electric currents. If, in the course of the electrical distribution system of a building, certain types of errors are made which create alternative paths for the return current from a circuit, a situation results which is commonly referred to as a “Net Current”.


The consequence of these errors, in addition to being violations of Code and posing both fire and shock hazards, is that the fields which result are both larger and decay more slowly that conventional “separation” fields. Conventional shielding is inefficient when combating net-current conditions. Instead, correct engineering practice requires that the wiring errors must be isolated and corrected prior to consideration of any other mitigation options, including shielding.

FMS offers Wiring Error Investigation services and typically works with a local electrician or contractor of the Client’s choice to isolate and correct Code violations. Detailed and systematic measurement of the electrical systems can point our specialized engineering staff to a speedy and accurate resolution of the problem.

Recent Projects


FMS as the EMF/EMI Consultant designed and installed the passive and active mitigation systems for this newly established interdisciplinary organization under the Office of Research of the University of California Irvine (UCI) to house state of the art electron-microscope labs (4 imaging cells). The project required analysis of interference potential of all internal and external emission sources, which included vehicle and facility elevators (DC), broadband electrical system (AC) sources, etc.

Harvard LISE

FMS was engaged as the project’s EMI Consultant by the project architect (Wilson Architects) to conduct an electromagnetic field (EMF) analysis in an existing laboratory (shell space) located in the basement level of the Harvard CNS facility.


Seattle Children’s Research Institute is currently in the construction phase of ”Building Cure”, a 540,000 square foot research building, which will be dedicated to developing therapies for children with diseases such as Cancer, Type 1 Diabetes and Sickle Cell Anemia.

Un. of Illinois Urbana-Champaign Electrical and Computer Engineering Bldg.

FMS was engaged to conduct a thorough assessment of the building’s design for EMI interference threat concerns to sensitive research equipment. A document review and extensive 3-Dimension computer simulation studies were conducted to evaluate EMF emissions from the building’s electrical distribution, mechanical and other systems.


Over its 20 years, FMS has successfully completed hundreds of EMI projects which included a diverse range of consulting and mitigation services.

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