An Explanation from Toronto Hydro:
Recent events such as the flood and the ice storm have had significant impacts on Toronto Hydro’s system. Standards today are now much more robust as a result of these events not to mention an ongoing experience/awareness/education around lifespans of our infrastructure, increased safety and improved resilience to severe weather both today and into the future. For example current modelling projections suggest a doubling of annual ice storms in the GTA by 2050 and there are many other climate change conditions forecasted to impact our service.
The pole’s we install today are wider and taller. We also use different span distances and provide for more anchoring (wires and poles). This storm hardening of our infrastructure is happening across the City of Toronto and in fact all across North America.
With regards to the undergrounding options there are additional factors to consider. Undergrounding our infrastructure often makes sense during new construction as opposed to existing. Establishing right of way, conduits, cable chambers and submersible transformer housings is significantly easier in areas where we don’t have to work with or around existing underground infrastructure such as water, sewage, telecommunications, transportation services, etc. Not to mention potentially having homeowners relocate service to their homes, possible electric panel box relocations, moving meters and stand masts, disturbing landscaping, etc. As soon as you start digging, these other services get disrupted and the project scope grows as does the budget.
Undergrounding is more resilient to most storms and weather impacts from climate change, however, flooding for example would have major implications to undergrounding service installations. Undergrounding service, if and when it fails, is also incredibly more time consuming to repair. When overhead wires fail, we can restore service fairly quickly, this is not the case with underground service.
Toronto Hydro and all distribution companies are measured by the Ontario Energy Board by two key factors: 1) SAIFI – frequency of outages across our service territory, and 2) SAIDI – duration of outages, this is measured in terms of minutes. A major flood like the one experienced in Etobicoke a few years ago, led to significant disruption in service, the primary issue was that the service to transfer high voltage power from Hydro One facilities on Kipling was underground and “filled up like a massive swimming pool”. Toronto Hydro’s ability to deliver service was fully intact however our service provider could not deliver power to us and therefore we couldn’t deliver it to the end user. Undergrounding is not always an easy solution.
The biggest and definitely most pressing issue deterring undergrounding is cost, it typically is 8-10x the cost of overhead wires.