On 04 March, after an appointment with the Cardiologist in downtown Toronto, I was driving back home. The roads were slippery due to the freezing rain we had the previous day and thus the traffic was moving slow. The traffic light I came upon was not functional and the traffic was further slowed down. After a kilometer, I found the road blocked by a police cruiser and at a distance I could see two fire tenders putting out the flames on the poles that housed the transformers. I took a diversion and then pulled up on the drive-through of the coffee shop, to be welcomed with a bold sign – ‘CLOSED – Due to power failure’.
The transformer fire in the area kindled my brain cells to write about it. As if to vent the vengeance caused by the transformer fires, snarling traffic and the aborted coffee mission, on reaching home, I decided to research the cause of the fire (which made my day awful). Thus this article was born.
On 03 March 2015, thousands of homes in Toronto were without power until 04 March evening, after a major power outage struck the city amid a blast of winter weather. The power outage was the result of over 50 electric poles housing transformers catching fire. Pole fires generally occur once every couple of weeks in a normal winter.
What caused this sudden outburst of pole fires now? Toronto area had temperatures of around minus 10 degrees Celsius for a fortnight without any precipitation; either in the form of snow or rain. The temperature on 03 March rose to zero degrees Celsius and there was freezing rain in the afternoon. During a freezing rain, raindrops become super-cooled while passing through sub-freezing layers of air. These drops freezes on impact with any surface they encounter. The resulting ice, called glaze, accumulates to a thickness of several centimeters.
Salt is spread on the roads to melt off the snow in sub-zero temperatures. The salt crystals are powdered under the tyres of the vehicles. This salt dust rises up and gets deposited on the vehicles, poles, pavements, road-signs, etc. This salt had built up on the joints on the transformer terminals throughout the extremely cold winter fortnight. As there was no rain or snow to rinse salt off the power lines, they accumulated, especially at the joints and corroded the insulation.
Once the freezing rain hit these salt covered joints, the salt dissolved in the water, making it a good electric conductor, but the ice ensured that it got stuck to the terminal. Thus the distance between the transformer terminals and the ‘earth’ reduced. This resulted in discharges of electricity (arcing), powerful enough to set the oil-filled transformers on fire. Normally, the air outside the solid insulator provides additional insulation.
The power outage caused the subway services to be suspended in some areas. The traffic lights in some areas did not function and a few shopping malls, restaurants and businesses closed down until the power was restored by 04 March.
The Winter of January-February 2014 brought with it the polar vortex, where in the cold winds from the North pole swept through Canada. This resulted in heavy snow and temperatures dropping to minus 40 degrees Celsius. Snow and ice weighed on power lines or snapped tree branches, which took transmission cables down with them, causing many power outages.
A freezing rain storm on March 2, 2007, resulted in a layer of ice several centimetres thick forming on the side of the 533-metre-tall CN tower and other downtown buildings. The sun thawed the ice, and winds of up to 90 km/h blew some of it away from these structures. There were fears that cars and windows of nearby buildings would be smashed by large chunks of ice. In response, police closed all the streets surrounding the CN tower. There were a few other cases of falling ice chunks reported in Toronto from the towers and high-rise buildings.
The modern buildings and towers are high-performance structures with double or triple-pane windows to reduce heat loss. The windowpane material is an efficient insulator. This results in no loss or transfer of heat to the outer side of the windowpanes causing the outer surface to be much cooler in comparison to the warmer inner surface. This causes accumulation of snow on these windowpanes. In the older buildings with less-efficient windows, enough heat escapes through the glass to melt the snow on contact. Further, protruding sun shades, end up creating ledges for snow and ice to accumulate.
Many suggestions were mooted to solve the ice-chunk problem of CN Tower – from manually chipping off to using laser or magnification of light to targeted problem areas to melt off the ice. The most practical one appears to be the one developed by Victor Petrenko, a professor at the Thayer School of Engineering at Dartmouth College. It is a thin film that uses an electric pulse to melt ice and snow in less than a second. It can be applied to any surface, including concrete and glass.. The pulse melts a thin layer of ice right as it meets the surface, forcing the ice to slide off.
The invention is already being used on the cables of the Uddevalla Bridge in Sweden, where built-up ice kept crashing down on vehicles in winter. The problem was solved by wrapping the bridge’s cables with a special stainless steel foil, which is heated with a short pulse of electricity. A transparent electrically conductive film is also being used in Russia to de-ice a huge glass dome over a mall.
The frequency of watermain breaks is greater in the winter months. The watermains are buried at about 10 feet below ground surface (much below the freezing level) to prevent the water from freezing. Low temperatures cause soil to freeze and expand, creating frost loading or force applied on the watermain. Prolonged periods of cold weather will result in an increase in the number of watermain breaks. Leaving a tap slightly open for a very thin stream of water and Insulating pipes that are outside or exposed to an uninsulated wall with foam pipe covers are some suggested methods to prevent watermain breaks. Opening kitchen, bathroom and laundry cabinet doors to allow warm air to circulate around the plumbing will also help.
Environment Canada has said that February 2015 that Toronto experienced, was the first in 75 years in which the temperature did not get above the freezing mark.
Always remember that winter is only temporary and think ahead a few months, the warmth of the Spring is on its way.