At Hydro Ottawa, delivering safe, reliable power is at the heart of what we do. And while no one likes a service interruption, sometimes we have to power off to power on, as planned maintenance is an essential part of ensuring long-term reliability.
Here’s a closer look at the most common types of planned maintenance work our crews and contractors perform.
Why planned maintenance matters
Planned maintenance helps keep our power system resilient, reducing the frequency and duration of unexpected outages. By proactively replacing aging equipment, trimming trees near power lines, and performing essential upgrades, we’re working to ensure a reliable power supply and a safe environment for our customers and crews. To conduct this work safely, it’s often necessary to de-energize the area first, which may require a planned outage.
Types of planned maintenance
No matter the type of maintenance work, safety is always Hydro Ottawa’s top priority. Crews follow strict protocols, wear personal protective equipment, and use barriers and clear signage to protect themselves and the public. Every step is designed to ensure a safe and efficient process while meeting the demands of the job.
Pole installation and/or replacement
Utility poles are essential for supporting overhead power lines, but over time, poles can degrade due to weather conditions, age, or environmental factors such as corrosion or pest damage. When a pole is damaged or reaches the end of its lifespan, replacement becomes necessary. Replacements are driven by emergencies, such as those resulting from vehicle collisions, which are addressed immediately, or through Hydro Ottawa’s critical pole program, which tests thousands of poles annually to identify those requiring maintenance. New pole installations also support grid expansion to meet Ottawa’s growing energy needs, such as in new residential or commercial developments. These planned pole maintenance jobs are carefully scheduled to minimize disruptions, with crews temporarily de-energizing the area to carry out the work.
New poles are selected based on specific site requirements, with materials ranging from wood to composite, steel, or concrete—each chosen for its durability and strength. These decisions are made within the framework of a heavily regulated industry, ensuring that every material is compliant with current standards and regulations, designed to protect both the environment and the public. Factors like weather ratings, budget and site conditions also guide the selection process. Poles vary in size and installation depth, typically buried 10 per cent of their height plus two feet (e.g., an 8-foot burial for a 60-foot pole). For a deeper dive about hydro poles, check our blog “Hydro poles: Where do they come from?”
Specialized equipment like cranes are often needed to handle taller or heavier poles, especially in constrained spaces like backyards. For excavation, Hydro Ottawa uses hydrovac trucks, which efficiently and precisely dig holes using high-pressure water and vacuum technology. This method is particularly effective in winter or tight spaces, reducing disruption compared to traditional digging.
The most significant challenge in pole replacements is the location of the work. Poles in high-traffic areas or on busy street corners require careful planning with the city to minimize disruption to the customers and the public, often involving civil onboarding, pre-construction meetings, obtaining street closure permits, setting up signage, and rerouting traffic to ensure safety. Where possible, Hydro Ottawa crews prioritize efficient sequencing, installing new poles first and transferring circuits to limit the number and duration of outages. Other challenges include weather conditions, such as snow or frozen ground in winter, which can complicate work. Despite these challenges, Hydro Ottawa crews are well-prepared to manage seasonal impacts, ensuring safe and efficient installations year-round.
Electrical equipment replacement and maintenance
Hydro Ottawa’s equipment replacement strategy combines proactive maintenance with customer-driven upgrades. This approach involves the careful assessment, removal, and installation of aging or faulty components within the electrical distribution system such as transformers, switches, circuit breakers, and connectors. Through routine inspections conducted on a three-year cycle across our service territory, Hydro Ottawa’s crews can identify equipment in need of replacement due to age, corrosion, or oil leaks, playing a critical role in preventing potential service disruptions. When components reach the end of their operational lifespan, crews safely de-energize the affected areas, using specialized tools and techniques to handle the often heavy and complex equipment.
For equipment located in high-traffic areas, additional preventative maintenance is essential. Hydro Ottawa’s annual insulator washing program, for example, targets areas near major highways where winter road salt can lead to accelerated corrosion. This program helps to protect insulators from salt accumulation, preserving equipment life and reducing the likelihood of failures due to environmental factors. Other types of maintenance include installing animal guards that are strategically placed around utility infrastructure to prevent wildlife, such as squirrels and birds, from nesting or foraging near electrical equipment.
Beyond these proactive measures, Hydro Ottawa also conducts customer-driven upgrades in response to specific needs, such as requests to increase electrical capacity from 200 to 400 amps. These requests often necessitate transformer replacements to accommodate higher energy demand, ensuring Hydro Ottawa’s infrastructure evolves in line with Ottawa's growing needs.
Tree trimming and removal
Tree trimming and removal at Hydro Ottawa involves managing the vegetation near power lines. Regular trimming prevents branches from interfering with power lines, while removal may be necessary for trees that pose a risk of falling, especially during storms or high winds, potentially leading to outages or safety hazards. This work requires careful assessment and expertise in both arboriculture and electrical safety, as crews must balance protecting tree health with the need to keep power lines clear.
When deciding whether a tree needs trimming or removal, Hydro Ottawa evaluates three key parameters to plan clearances and trimming schedules in line with safety standards:
- Vegetation management units (VMUs): These are designated areas within our service territory, each with a specific maintenance cycle (every two or three years). Trees in VMUs with longer cycles may require greater clearance to account for growth between trims.
- Tree species: Fast-growing trees need more initial clearance to prevent regrowth from encroaching on power lines, whereas slow-growing trees may need less frequent maintenance.
- Line voltage: High-voltage lines (e.g., 44,000 volts) require more clearance than lower-voltage lines (e.g., 4,000 volts) due to increased safety risks and operational needs.
For customer-related requests involving tree trimming/removal work not performed by Hydro Ottawa, a minimum 10-foot clearance is required from high-voltage lines to ensure a safe workspace for contractors or any hired personnel.
Safety is paramount when working with trees near power lines. Arborists face unique hazards, including working at significant heights, in adverse weather, using chainsaws, and operating in close proximity to live electrical wires. All trimming is performed by expert contractors who follow strict action plans to ensure safety at each job site.
To streamline tree management, Hydro Ottawa has adopted satellite imaging technology. This system scans the electrical grid twice per year, identifying high-risk areas and potentially dead or dying trees. By analyzing chlorophyll levels in trees under infrared light, the technology can flag vegetation that is still alive but showing early signs of decline, allowing for proactive trimming or removal. This approach not only optimizes the trimming cycle but also highlights environmental patterns, such as stress caused by extreme weather or pests, giving Hydro Ottawa a clearer picture of potential challenges across the grid.
While standard trimming doesn’t typically require environmental assessments, Hydro Ottawa takes additional measures for certain protected species. For example, butternut trees, which are considered endangered, require special assessment and approval from the Ministry of Natural Resources before any work can proceed. Additionally, satellite imaging provides insights into environmental changes that could impact tree health, allowing Hydro Ottawa to address any emerging ecological issues while maintaining the safety and reliability of the electrical grid.
Maintenance hole upgrades
Hydro Ottawa maintenance covers are chambers that connect vast duct structures and substations to deliver electricity to customers across the city. Maintenance hole upgrades are often necessary due to the wear and degradation of key structural components, especially in high-traffic areas. In urban locations, the regular use of salt during winter months accelerates corrosion of internal steel beams and the deterioration of concrete. This process weakens the roof and internal walls of the maintenance holes. Regular inspections assess the condition of maintenance holes using a grading scale from A to E. Ratings closer to C or D indicate areas that may need immediate or future repairs. These repairs can range from partial restoration, such as reinforcing concrete, to complete rebuilds when severe structural issues are found.
During upgrades, crews take extensive steps to minimize disruptions to the surrounding areas, particularly in busy downtown zones. Working closely with city officials, teams schedule maintenance around local events to reduce the impact on businesses and residents. In most cases, maintenance hole work does not require a power outage, which helps minimize inconvenience for customers and alleviate concerns about service interruptions. However, businesses and residents in the affected area are given advance notice so they can prepare if necessary.
The complexity of maintenance hole upgrades lies in managing pedestrian and vehicle traffic, particularly in the densely populated downtown core. Despite clear signage and fencing to direct the public around construction zones, people sometimes attempt to bypass barriers, creating safety risks. The confined space of a maintenance hole, often filled with live cables, adds further challenges. Specialized equipment and personal protective gear are necessary, and maintaining safety standards in these conditions is critical. Additional measures are taken to secure both the work site and the surrounding area.
Learn more about maintenance holes on our blog, “Hydro Ottawa’s chamber of secrets.”
Cable replacement
Like all equipment, cables (whether overhead or underground) can degrade over time or get damaged, and need to be replaced to maintain reliable service. Replacing these cables requires a planned outage to protect both our teams and the integrity of the system as they handle the high-voltage lines.
Several indicators help determine when cables need replacement, including equipment fault histories, cable testing results, and estimates of equipment life spans. Hydro Ottawa’s assets department tracks and assesses these factors to prioritize replacement projects each year. This approach helps ensure that upgrades address the most critical needs in a timely manner, improving system reliability and reducing the likelihood of unplanned outages.
The logistics of cable replacement involve extensive planning and coordination to upgrade infrastructure to modern standards. In the past, cables were often buried directly in the ground, but today, best practice includes placing cables within protective conduits - pipes around 4 inches in diameter, made of materials like polyvinyl chloride (PVC) or high-density polyethylene (HDPE), which provide easier access for future repairs or replacements without additional excavation. Although conduit installation requires substantial trenching, the long-term benefit is minimized disruption for future upgrades. The process, however, can be challenging, as it often requires access through residential properties, driveways, and yards, and necessitates clear communication with homeowners about the project's scope and duration.
Innovative techniques are used to enhance safety and efficiency during cable replacements. Crews follow strict safety protocols, especially when working around live, high-voltage cables, using rubber gloves, safe distance practices, and de-energizing systems as necessary. While excavation around the site does not require a temporary outage, one is required on the day crews work directly on the transformer, affecting the customers served by that equipment. Crews can sometimes face unexpected underground obstacles, such as tree roots, rocks, or old foundations, which may not have been reflected in project plans. These challenges require flexibility and on-site problem-solving to maintain safe and efficient progress on cable replacement projects.
How we minimize impacts to customers
We understand that even planned outages can be inconvenient. Planned power interruptions are carefully reviewed and scheduled to ensure that any impact is minimal and enables the work to be completed as quickly and as safely as possible, and with our customer’s best interest in mind.
All impacted customers are contacted by phone, text or email - depending on the communication preferences indicated on their MyAccount profile - so make sure your communication preferences are up to date. You can also stay informed on upcoming maintenance by signing up for Outage alerts or by visiting our Scheduled power interruptions webpage. This way, you’ll have the information you need to plan around any service interruptions.