Data centre and server room electrical work in Calgary

CCT 01From a server closet to a data hall

“Data centre” covers facilities that differ by orders of magnitude, and the electrical questions change with scale.

• Server closet or network room. A few racks inside an office or clinic, often on the tenant’s panel. The issues are a dedicated circuit or two, a small UPS, cooling, and whether the landlord’s electrical room can supply more. It is usually part of a tenant improvement.
• Dedicated computer room. A room with its own distribution, a larger UPS, often a standby generator and precision cooling. Now the building service, the transfer equipment and the maintenance strategy all matter.
• Colocation suite or data hall. Many racks, redundant utility and generator paths, and a load large enough that the utility plans for it. The power supply is a project of its own, sometimes years ahead of the building.

At every scale the load has two parts: the IT equipment itself and the cooling that removes its heat. Every kilowatt the servers draw becomes heat the mechanical system must reject, so the electrical capacity has to carry both. Size the service on a qualified load calculation that includes cooling, not on the IT figure alone.

CCT 02The critical power chain, and where redundancy goes

Critical power runs through a chain: the utility service, the main switchgear, an automatic transfer switch to the generator, the UPS, then distribution to power distribution units and the rack power strips. Each link can fail or need maintenance, and the design decides which failures the room survives.

Redundancy is described in plain notation rather than numbers of nines:

• N is exactly enough capacity for the load. Any failure or maintenance outage drops the load.
• N+1 adds one spare module, such as one more UPS module or generator than the load needs. One unit can fail or be serviced without an outage, but the shared parts (a single bus, a single transfer switch) remain single points of failure.
• 2N is two complete, independent paths, typically an A and a B feed to dual-corded equipment. Either path can be shut down for maintenance.
• Concurrent maintainability means every component can be taken out of service for planned work without dropping the load. It is a test of the whole design, including bypasses and cable routes, not of the UPS alone.

Be wary of any uptime percentage attached to a design category. Availability depends on the equipment, the maintenance and the people as much as on the diagram. Ask the designer instead to walk through a list of failure and maintenance scenarios and show what stays energized in each.

CCT 03UPS, batteries and standby generators

The UPS bridges the gap between a utility failure and the generator taking load, and it conditions power the rest of the time. Its battery runtime should cover generator start, transfer and a margin for a failed first start, and should be set by the design, not by habit. Plan for:

• Bypass arrangements. An internal static bypass and an external maintenance bypass, so the UPS can be serviced or replaced without shutting down the room.
• Batteries. Chemistry, room ventilation and fire separation, replacement cycles and monitoring are design decisions with code and insurer implications.
• Power quality. UPS and IT loads affect the building’s power factor and harmonics. ENMAX requires customers to keep power factor at 90% or better, and can require corrective equipment at the customer’s expense.¹

The standby generator and its automatic transfer switch carry the load through longer outages. Keep the IT standby system distinct from any life-safety emergency power: they are treated differently under the electrical code, and life-safety loads have priority. Calgary Fire Department’s guidance cites CSA C282-15 for emergency generator maintenance,² while CSA’s current edition is C282:24,³ so specify the edition the fire code references. Calgary’s January design temperature is −30 °C,⁴ which makes block heaters, fuel choice, enclosure heating and cold-start testing part of the design. The generator and ATS cost guide covers what drives the price.

Reel 01 · Switchgear lineup · illustrative film

CCT 04How ENMAX sees a server room: kVA, the ratchet and large load

A data load runs day and night, which changes how the utility bills it. ENMAX Power bills commercial demand in kVA, not kW. Billing demand is the greatest of metered, ratchet or contract demand, and the ratchet is 90% of the highest kVA demand in the last 365 days.⁵ One peak during commissioning or a cooling failure can set the demand bill for a year, so plan load bank tests and cut-overs with the meter in mind.

• Rate class. A site moves to D310 Large Commercial once it registers a monthly peak above 150 kVA twice in 365 days, at secondary voltage.⁵ D310 carries a service charge of $26.041806 a day plus per-kVA facilities and demand charges.⁵
• Metering. ENMAX installs interval meters at new sites planned at 150 kVA or more.¹ ENMAX requires a CT request form and checklist for services over 200 A,⁶ covered in the CT metering guide.
• Large load. ENMAX treats projects above 1 MVA, or 720 kVA in the downtown core, as a large-load project type in its intake process.⁷ Raise these early; capacity at the location can decide the site.
• Investment. Medium and large commercial customers can take ENMAX investment of $367 per kVA of minimum contract demand on a 15-year agreement, up to 80% of anticipated maximum demand.⁸ That is a credit against ENMAX’s cost, paired with a long commitment to pay for the demand.

Energy is a separate purchase. A site whose annual consumption is forecast under 250 MWh is eligible for the Rate of Last Resort;⁹ as arithmetic only, a hypothetical load drawing a steady 30 kW all year uses 30 × 8,760 = 262,800 kWh, just over that line. The ENMAX commercial connection guide covers the process step by step.

CCT 05Alberta’s large-load limits for data centres

At the scale of hyperscale and AI data centres, the constraint is the provincial grid, not the building. On June 4, 2025 the Alberta Electric System Operator set an interim limit allowing up to 1,200 MW of large load projects, such as data centres, to connect between then and 2028.¹⁰ The interim approach applied to load projects of 75 MW or more.¹⁰

Phase 1 is complete. All 1,200 MW was allocated to two projects, the GLDC load (970 MW) and Keephills Data Centre Phase I (230 MW), and other requests move to Phase 2.¹¹ Demand has not slowed: the Government of Alberta reports about 19,565 MW of new data centre load requesting connection on the AESO list of July 30, 2026.¹²

The province has also changed the order of the queue. According to the Government of Alberta’s summary, the Data Centre Regulation, in force since June 2026, puts projects that pair their demand with dedicated new generation or storage at the front of the connection line.¹² This page relies on that summary; read the regulation itself before relying on it for a project.

CCT 06Permits, drawings and commissioning

Critical power work is permitted and inspected like any other commercial electrical work, with more paperwork because the equipment is larger.

• Drawings at 600 A and above. Calgary requires plans for new construction or service upgrades of 600 A and higher, including all high-voltage installations.¹³ The single-line diagram must show fault current at every overcurrent device and any series-rated combinations.¹³
• Separate permits. Base-building work and tenant-space work take separate electrical permits in Calgary,¹³ which matters when a colocation tenant fits out a suite in a landlord’s building.
• Fire alarm and suppression interfaces. Altering or installing a fire alarm needs both an electrical and a building permit,¹³ and suppression releases and emergency power-off controls have to be coordinated with it.
• Code edition. Installations permitted now follow the 2024 Canadian Electrical Code, CSA C22.1-24.¹⁴

Commissioning is where redundancy is proved. Beyond each component’s start-up, an integrated systems test pulls the utility and watches the transfer, the UPS and the generators carry a real or load-bank load. Write the test scenarios into the contract, agree who witnesses them, and book the utility and the load bank with the demand ratchet in mind.

CCT 07Data centre scopes and the services they draw on

Most server room work in Calgary starts in the first row and grows into the second. Before a room outgrows its panel, check the building’s recorded peak against its service rating; the service capacity calculator below does the arithmetic. Continuous loads also change maintenance: equipment that never turns off can only be serviced if the design allows it, which is the case for building concurrent maintainability in from the start.