Case 2.  Office Building in Kansas City, Missouri...

Clients' Concerns:  Relatively high magnetic fields in the first floor offices due to a large transformer vault located directly below.  Many computers were having severe interference problems.  Clients also wished to reduce EMF levels to employees.

Source of the Magnetic Fields:  While magnetic fields were being emitted from several sources in the transformer vault, the largest single source was from the particular way that the secondary cables were arranged in the ladder trays above the transformers.

Solution Implemented:  The most cost effective mitigation for this particular case was to simply reconfigure the secondary cables above the transformers, thus reducing the EMF emissions through automatic self-cancellation.  See the two pictures below...

This is a picture of the transformer vault before the fix.  The offices were located directly above these transformers.  The main source of the EMFs was from the large electrical cables in the ladder racks above the transformers.  (Please click image for full-sized picture.)

This is a picture taken after the fix.  Some of the large secondary cables above the transformers have been replaced and rerouted to provide for automatic self-cancellation.  This simple modification was quite effective, yet much less costly than shielding would have been.  (Click image for full-sized picture.)