Toronto’s CN Tower acts as a lightning laboratory, teaching scientists how to protect delicate electronic equipment against high-voltage surges, according to a study by U of T researchers, published in the Journal of Electrostatics.
Wasyl Janischewskyj, a professor emeritus at U of T’s Edward S. Rogers Sr. department of electrical and computer engineering, and his colleagues found that the unusual structure of the CN Tower obstructs the downward flow of electricity and causes the current to peak in certain areas. Identifying such patterns is critical to determining over-voltages that may occur as the result of lightning strikes to tall structures, and to designing protective measures for today’s increasingly sensitive electronic equipment.
“This study gives us a better understanding of the electromagnetic field caused by a lightning strike to a tall structure,” says Janischewskyj. “This can help designers incorporate the appropriate precautions, such as enclosures for sensitive equipment or special diodes that would ‘short out’ rather than cause an over-voltage inside the equipment.”
Lightning strikes the 553-metre-high CN Tower an average of 75 times per year. To direct the current into the ground, metallic conductors run down the tower and are connected to 42 grounding rods buried deep below the surface.