Overhead Transmission Line Near a Commercial Center (Office Buildings)
An existing overhead transmission line (120–315 kV) runs close to an office building in a commercial area in Ontario, Canada. The center of the high-voltage line is approximately 100 feet (30 meters) from the building. Ground-level measurements near the structure indicated a potential for exceeding recommended limits in other countries. As elevation increases and approaches the height of the transmission lines, the potential for stronger magnetic fields also rises.
Magnetic Field Levels Measured at Various Distances from the Line Center (End of November)
At a distance of 12 m from the centerline of the transmission line, a magnetic field level of 14.2 milligauss was measured.
At 17 m, the measured field was 11.3 milligauss.
At 23 m, the measured field was 8.8 milligauss.
At 28 m, the measured field was 7.2 milligauss (the building is located at a distance of 30 m).
At 33 m, the measured field was 6 milligauss.
