Ontario

How you connect

A large data centre usually connects at transmission voltage, and IESO assesses any load over 10 MW. You work with two parties at once: IESO, which assesses whether the grid can take the load, and the transmitter, usually Hydro One, which designs and builds the connection. You pay for any grid reinforcement your project triggers. There is no cap on data centres and no allocation call, though the draft rules would rank projects where capacity is short.

IESO is also adding technical requirements for large computing loads, including when they must stay connected through a voltage disturbance.

The provincial rules

Since December 2025 the Electricity Act has let the province set requirements that a designated data centre must meet before it connects. No regulation designating any data centre exists yet. Ontario released a draft Data Centre Playbook in August 2026, and comment closed on 12 September. The size thresholds it relies on are left to a future regulation. The province’s announcement also proposes priority for projects with closed-loop cooling.

Energy Minister Stephen Lecce has said data centres must show community benefits and pay the full cost of the power they use. “It is not your right.”

Local bylaws

Oakville paused new data centres for a year in August 2026, extendable to two. Mississauga paused data centres of 10 MW or more for up to a year on 16 September 2026, which holds up Prologis’s proposed project in Meadowvale, which Prologis has put at 40 MW.

Bringing your own power

Legal. Ontario requires a licence to sell power, not to make it for your own use. Large tech companies are looking at it to get around transmission waits, and the draft rules would weigh a project’s own-power plans as part of approval.

Cost and timing

There is no data centre rate yet, but the province has proposed higher rates for new data centres above 1 MW, in a separate rate class without access to the Industrial Conservation Initiative. Today costs come through the market price, the Global Adjustment, connection payments and expansion deposits, and facilities over 10 MW pay for their own impact assessments. IESO’s figure for connecting a new facility is more than three years.

What has happened

1. 16 September 2026 Mississauga pauses data centres of 10 MW or more for up to a year
2. 12 September 2026 Comment closes on Ontario’s draft data centre framework
3. 3 September 2026 IESO posts revised technical requirements for large computing loads
4. 13 August 2026 Ontario releases its draft Data Centre Playbook
5. 11 August 2026 Oakville pauses new data centres for a year
6. 28 July 2026 Energy minister on grid access for data centres: “It is not your right”