Responsible Electricity Transmission for Albertans
Tornadoes Topple High Voltage Towers
There are many examples of tornadoes and other high wind storms toppling high voltage transmission towers and lines.
One of the most recent tornadoes in Canada occurred July 23, 2011 in Lambton County, Ontario. Environment Canada confirmed that a force F2 tornado with wind speeds between 180 and 230km/hour touched down and toppled 8 high voltage steel transmission towers. The downed towers and power lines cut electricity to 13,000 customers from Sarnia to London. There was significant damage and destruction but fortunately no deaths or injuries were reported. A Hydro One spokesperson said the amount of damage to the towers was highly unusual, as they are built to withstand very strong winds.
Similar assurances are given by other transmission facility owners, namely that their high voltage towers are built to withstand tornadoes and other high winds. However, in 1987, a force F4 tornado touched down in Edmonton, Alberta, causing between $6 million and $8 million damage to TransAlta’s high voltage transmission equipment. The storm destroyed 49 240kV double circuit steel towers, 17 138kV double circuit steel towers, and 134 138kV single circuit wooden structures. Winds were estimated as high as 330km/hour. A total of 27 people were killed, nearly 300 were injured, and 750 families were left homeless. See this Fact Sheet for further details of this tornado and other high voltage power lines brought down by severe weather conditions.
There is much speculation that tornadoes, once touched down, will follow the path of high voltage transmission lines such as was the case with the Edmonton tornado in 1987. This is just one of the many reasons residents and businesses are worried about being located near high voltage power lines. Common sense suggests that new high voltage lines should not be built near homes, schools, daycare centres or any other facilities with high numbers of people. As a result, one would think that both transmission facility owners and governments would want to exercise caution when siting new high voltage lines.
Unfortunately, AltaLink, EPCOR, the Alberta Electric System Operator, and the Alberta Government all prefer the proposed 500kV double circuit Heartland Transmission Line to be built above ground next to 5,194 homes, several schools and daycare centres, and a hospital in Edmonton, Sherwood Park and Sturgeon County. An above ground high voltage power line with towers up to 76m tall built so close to so many people would be an accident waiting to happen, should another tornado ever touch down in the Edmonton area.
New high voltage power lines built near so many people must be buried. Underground lines do not blow over in wind storms and have many other benefits when compared to overhead lines.