How do you energize a substation that powers half of Calgary’s downtown?
This fall, ENMAX is embarking on a new phase of the Substation No. 1 replacement project – moving the power supply from one substation to another.
It’s called a cutover and while the name sounds simple, the work behind it is anything but. Essentially, crews will work to unplug the 100-year-old original substation and plug Calgary’s downtown electricity network into the new one across the street. But, instead of a simple plug, crews will be transitioning six high voltage transmission lines and 24 distribution feeder lines that supply power to nearly half of downtown Calgary.
The work ahead
Starting September 5, crews will begin transferring lines, a project that will unfold over the next 10 months, wrapping up in summer 2026.
“This is the first step to energizing the new substation,” said Alyssa Howland, Substation No. 1 replacement project manager. “Everything up to this point has been building and testing, now we’re actually starting the process of energizing the new substation and putting it into service.”
The process includes:
- Temporarily de-energizing the old lines (without affecting customers)
- Excavating streets to reach underground duct banks that carry cables.
- Pulling new cables into the substation
- Splicing and connecting the new cables inside manholes
- Running tests to ensure everything works before powering the lines back on.
What you need to know
Traffic impacts: crews will need lane closures on 7 Street SW and 9 Avenue SW. To reduce disruptions, they’ll be working seven days a week to get the work done as quickly and safely as possible.
Behind the construction fences, crews will excavate the road and rebuild existing ducts to access the transmission lines and carefully splice and connect new cables — the most critical step to bring the new substation online.
Powering Calgary’s future
Substation No. 1 has reliably powered downtown Calgary for over a century. Its replacement is one of ENMAX’s largest infrastructure projects to date and will ensure Calgary’s core has the reliable electricity it needs to support our city for decades to come.
“This whole project has been about building a new substation that will support the electricity system for Calgary’s future while minimizing impacts to customers today,” said Greg Retzer, Executive Vice President, ENMAX Power. “Replacing Substation No. 1 ensures the next century of growth downtown is supported by modern, reliable infrastructure.”
When the cutover is complete, downtown Calgary will be connected to a stronger, more modern grid.