Canadian winters can be tough, especially on our roads and highways.
In an effort to keep our roads safe, municipal crews use various techniques beyond plowing snow, which include sanding, salting and the application of salt brine ahead of snowfalls. The use of salt brine in recent years has increased the normal contamination that accumulates on our poles – contained in the mist from the surrounding environment – especially on high traffic roadways.
This road salt residue and other contaminants accumulate on the ground, on hydro poles and on the equipment attached to them, such as line insulators which prevent electricity from travelling from power lines to the pole. When the temperature moves towards the 0°C mark from below freezing, this buildup of road salt residue, combined with the presence of moisture, creates an environment that can give rise to pole fires.
During winter and spring thaws, snow and ice begins to melt and when mixed with the accumulated salt residue on roadways, can be “stirred” up into the atmosphere coating our poles and insulators. We’ve all experienced these conditions when driving and use considerable windshield washer fluid to keep our automobile windshields clean. When this semi-conductive coating covers our poles and insulators, electricity now has the opportunity to travel from the power line along the insulator and onto the metal bolt attaching the insulator to the wood pole. The metal bolt heats up and the wood pole can begin to char, smoulder, and eventually could catch fire. Poles can be severely damaged during fires, and the fire has to be extinguished before crews can repair or replace the pole and restore power to affected customers.
“Poles that are most at risk are located in high-traffic, high-speed areas, such as along major highways, highway overpasses and major in-town roadways”
– John McClean, Vice President, Centralized Operations Services
While wood poles are most at risk of fire during this time of year, because the thaws result in the presence of moisture that conducts electricity, similar conditions may also occur in other seasons during humid or foggy conditions, or if there is rain or freezing rain.
What does Alectra Utilities do to avoid pole fires?
Alectra Utilities has a regular program for high-pressure washing our poles and substation equipment, typically conducted during the spring and fall. To further reduce the risk of pole fires, we take opportunities in the winter, when temperatures warm up sufficiently, to wash away the buildup of salt residue and other contaminants. Efforts are focused on higher-risk areas near the 400-series highways and major roadways, where mist from the road rises into the air.
Alectra Utilities is also investigating the types and ages of poles and line hardware that were involved in the pole fires, with a view to assessing whether improvements could be made to further reduce the risk of pole fires.