Case 1.  Large Internet Facility near Los Angeles...

Clients' Concerns:  Nearby high-tension power lines were causing interference with the operation of computers in a large section of the facility near the power lines.  Clients also wished to reduce EMF levels for employees.

Source of the Electromagnetic Interference:  Our testing confirmed that the computer interference was indeed caused by the magnetic fields from the adjacent power lines.  Our analysis also verified that the interference was not significantly due to internal sources such as electrical wiring, panels, grounding, or equipment within the building.

Solution Implemented:  The most cost effective mitigation for this particular case was to install a large scale custom magnetic field cancellation system.  Such systems utilize modern electronic technology to create an opposing magnetic field which "cancels out" the power line's field.  In this case, shielding would have been a relatively difficult and expensive option.  For further detail, see the pictures below...

This is a picture on the roof of the building. You can see the close proximity of the power lines.  Many computers in the portion of the facility near the power lines, on both first and second floors, were being affected by interference.  The conduit seen here is part of the new cancellation system that we installed.  This system uses a series of small "sensor coils" inside the building to detect and monitor the magnetic fields from the power lines.  The system then sends a low voltage current through a specially designed loop of "cancellation wires" which encircle the problem areas.  This precisely controlled current then creates an opposing magnetic field which cancels the power line field in the desired areas.  (Please click image for full-sized picture.)

This is a picture of the facility taken from underneath the power lines.  The large window areas made it very impractical to install shielding for the magnetic fields.  And regardless of the windows, adequate shielding material for this building would have cost at least 10 times more than the cancellation system itself.  One of the conduits for the system can been seen running up the outside wall in the center of this picture.  While this conduit could have been installed inside the walls, the owners wanted to minimize costs, so the conduit was mounted externally and later painted to match the building.  (Click image for full-sized picture.)

This is another picture on the roof.  It shows more of the cancellation conduit system (in the foreground).  Because of the high number of square feet needing treatment, this particular project utilized six independent cancellation systems.  They were installed side by side across the length of the building to cover the entire area affectively.  Each system had its own sensor, electronics, and cancellation conduit.  (Click image for full-sized picture.)