Overhead Transmission Line Near Residential Area
An existing overhead transmission line (120–315 kV) runs close to a residential neighborhood in Ontario, Canada. The center of the high-voltage line is approximately 100 feet (30 meters) from the property boundary. Measurements taken during calm weather conditions showed normal values, while measurements during winter weather indicated higher readings. It is important to note that these values vary according to electricity demand, so it can be assumed that during extreme weather conditions, the values will increase.
In many cases, the timing of the measurements is critical; therefore, it is common practice to assess the potential impact of the lines rather than making decisions based on a single instantaneous measurement.
Magnetic Field Levels Measured at Various Distances from the Line Center (End of November)
At a distance of 0 m beneath the centerline of the transmission line, a magnetic field level of 23 milligauss was measured.
At 7.5 m, the measured field was 21.3 milligauss.
At 15 m, the measured field was 18.5 milligauss.
At 22.5 m, the measured field was 15.7 milligauss.
At 30 m, the measured field was 13.3 milligauss.
