Hydro One (HRNNF) files to build $3B Ontario power lines

Rhea-AI Filing Summary

Hydro One Limited reports that subsidiary Hydro One Networks Inc. has filed two leave-to-construct applications with the Ontario Energy Board to build the Northeast Power Line and the Longwood to Lakeshore Transmission Line.

The Northeast Power Line is a single-circuit 500-kV transmission line between Hanmer TS and Mississagi TS, with an estimated cost of about $1.8 billion and planned completion in 2029. It is expected to increase transfer capability between northeast and northwest Ontario by approximately 900 MW. The Longwood to Lakeshore line is another single-circuit 500-kV project between Longwood TS and Lakeshore TS, representing about a $1.2 billion investment, anticipated to bring about 550 MW of electricity to southwest Ontario, with completion expected in 2030.

Both projects use Hydro One’s First Nation Equity Partnership Model, giving proximate First Nations the opportunity to invest in a 50 per cent equity stake in the transmission line component of each project. Hydro One highlights its scale with 1.5 million customers, $39.7 billion in assets as of December 31, 2025, 2025 annual revenues of $9 billion, and $3.4 billion invested in its transmission and distribution networks in 2025.

Insights

Infrastructure and utilities analyst

Hydro One outlines roughly $3 billion of new regulated transmission projects pending Ontario Energy Board approval.

Hydro One is pursuing two large 500-kV transmission lines: the Northeast Power Line at about $1.8 billion and the Longwood to Lakeshore line at about $1.2 billion. Both are subject to Ontario Energy Board leave-to-construct approval under Section 92 of the Ontario Energy Board Act, 1998.

The Northeast project is expected to add roughly 900 MW of transfer capability between northeast and northwest Ontario, while the Longwood to Lakeshore line is anticipated to bring about 550 MW to support agri-business and manufacturing in southwest Ontario. Timelines extend to 2029 and 2030, respectively.

A notable feature is the First Nation Equity Partnership Model, under which proximate First Nations may invest in a 50 per cent equity stake in the transmission line component of each project. Actual financial impacts will depend on regulatory approvals, final project costs and the structure of any First Nations equity participation as disclosed in future filings.

Key Figures

Northeast Power Line cost: $1.8 billion Longwood–Lakeshore line cost: $1.2 billion Transfer capability increase: 900 MW +5 more

8 metrics

Northeast Power Line cost $1.8 billion Approximate investment for 500-kV line, completion planned 2029

Longwood–Lakeshore line cost $1.2 billion Approximate investment for 500-kV line, completion expected 2030

Transfer capability increase 900 MW Expected added transfer capability between northeast and northwest Ontario

Capacity to southwest Ontario 550 MW Anticipated additional electricity to region from Longwood–Lakeshore line

Total assets $39.7 billion Assets as at December 31, 2025

Annual revenues $9 billion Hydro One revenues in 2025

2025 network investment $3.4 billion Invested in transmission and distribution networks in 2025

Goods and services purchased $3.0 billion Goods and services bought in 2025

Key Terms

leave-to-construct applications, Ontario Energy Board, First Nation Equity Partnership Model, medium term notes, +1 more

5 terms

leave-to-construct applications regulatory

"announced it has filed two leave-to-construct applications with the Ontario Energy Board"

Ontario Energy Board regulatory

"filed two leave-to-construct applications with the Ontario Energy Board (OEB)"

First Nation Equity Partnership Model financial

"Through Hydro One’s First Nation Equity Partnership Model, proximate First Nations will have the opportunity"

medium term notes financial

"Hydro One Limited’s common shares are listed on the TSX and certain of Hydro One Inc.’s medium term notes are listed"

Medium term notes are debt securities companies or governments sell to borrow money for a few years—generally from about two to ten years—paying regular interest and returning your principal at maturity. Think of them like an IOU with a set length and interest schedule that investors can buy to earn income; they matter because their credit quality, interest rate type (fixed or floating) and maturity affect how much return and risk an investor takes on compared with short-term bills or long-term bonds.

forward-looking information regulatory

"This press release may contain “forward-looking information” within the meaning of applicable Canadian securities laws"

Forward-looking information are predictions, plans, estimates or expectations about a company’s future performance, results or events, such as sales forecasts, project timelines, or anticipated costs. It matters to investors because these statements guide expectations but rely on assumptions and uncertain factors—like a weather forecast for a business—so investors should treat them as informed guesses rather than guarantees and consider the risks and possible changes behind the numbers.

Form 6-K: How Foreign Companies Report to the SEC →

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

Pursuant to Rule 13a-16 or 15d-16

under the Securities Exchange Act of 1934

For the month of: May 2026

Commission File Number: 333-225519-01

HYDRO ONE LIMITED

(Translation of Registrant’s name into English)

483 Bay Street, South Tower, 8th Floor, Toronto Ontario M5G 2P5 Canada

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F ☐   Form 40-F ☒

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

HYDRO ONE LIMITED

/s/ Cassidy McFarlane

Name: Cassidy McFarlane

Title: General Counsel

Date: May 19, 2026

EXHIBIT INDEX

99.1 News Release dated May 19, 2026

Exhibit 99.1

Hydro One seeks approval from the Ontario Energy Board to build the Northeast Power Line and the Longwood to Lakeshore Transmission Line

Once built, the lines will support local industry, agri-business and a strong and self-reliant economy

TORONTO, May 19, 2026 – Today, Hydro One Networks Inc. (Hydro One) announced it has filed two leave-to-construct applications with the Ontario Energy Board (OEB) to seek approval to build the Northeast Power Line and the Longwood to Lakeshore Transmission Line.

The Northeast Power Line is a single-circuit 500-kilovolt (kV) transmission line between Hanmer Transformer Station (TS) in Greater Sudbury, and Mississagi TS near Wharncliffe. This critical infrastructure is expected to reinforce the transmission system’s transfer capability between northeast and northwest Ontario by approximately 900 megawatts (MW). Construction of the approximately $1.8-billion transmission line is planned to be completed in 2029.

The Longwood to Lakeshore Transmission Line is a single-circuit 500-kV transmission line between Longwood TS in the Municipality of Strathroy-Caradoc and Lakeshore TS in the Municipality of Lakeshore. The approximately $1.2-billion investment is anticipated to bring about 550 MW of electricity to the region, to support local jobs and the agri-business and manufacturing sector in southwest Ontario. It’s expected to be completed in 2030.

Through Hydro One’s First Nation Equity Partnership Model, proximate First Nations will have the opportunity to invest in a 50 per cent equity stake in the transmission line component of each project. Together, Hydro One and the proximate First Nations will continue to collaborate on the planning, development and construction of the lines.

“Electricity demand in Ontario is increasing. These lines are part of one of the largest transmission line infrastructure investment portfolios in Canada that we are advancing together with First Nations,” said Ryan Docherty, Executive Vice President, Capital Portfolio Delivery, Hydro One. “Hydro One’s success is tied to Ontario’s success. Together, we are helping build a stronger and more self-reliant economy that advances local priorities, supports good jobs and drives economic growth, while continuing to deliver value for the people of Ontario.”

Filing a leave-to-construct application under Section 92 of the Ontario Energy Board Act, 1998 is required for electricity transmitters in Ontario to obtain approval from the OEB to construct, expand or reinforce the transmission system. The application includes details on the project’s route, design, timing and cost.

For information on the projects, visit the Northeast Power Line webpage and the Longwood to Lakeshore Transmission Line webpage.

Hydro One Limited (TSX: H)

Hydro One Limited, through its wholly-owned subsidiaries, is Ontario’s largest electricity transmission and distribution provider with 1.5 million valued customers, $39.7 billion in assets as at December 31, 2025, and annual revenues in 2025 of $9 billion.

Our team of 9,600 skilled and dedicated employees proudly build and maintain a safe and reliable electricity system which is essential to supporting strong and successful communities. In 2025, Hydro One invested $3.4 billion in its transmission and distribution networks, and supported the economy through buying $3.0 billion of goods and services.

We are committed to the communities where we live and work through community investment, sustainability and diversity initiatives.

Hydro One Limited’s common shares are listed on the TSX and certain of Hydro One Inc.’s medium term notes are listed on the NYSE. Additional information can be accessed at www.hydroone.com/, www.sedarplus.com or www.sec.gov.

For More Information

For more information about everything Hydro One, please visit www.hydroone.com where you can find additional information including links to securities filings, historical financial reports, and information about the Company’s governance practices, corporate social responsibility, customer solutions and further information about its business.

Forward-looking statements and information:

This press release may contain “forward-looking information” within the meaning of applicable Canadian securities laws and “forward-looking statements” within the meaning of applicable U.S. securities laws (collectively, “forward-looking information”). Statements containing forward-looking information are made pursuant to the “safe harbour” provisions of applicable Canadian and U.S. securities laws. Words such as “expect”, “anticipate”, “intend”, “attempt”, “may”, “plan”, “will”, “can”, “believe”, “seek”, “estimate”, and variations of such words and similar expressions are intended to identify such forward-looking information. These statements are not guarantees of future performance or actions and involve assumptions and risks and uncertainties that are difficult to predict. Therefore, actual outcomes and results may differ materially from what is expressed, implied or forecasted in such forward-looking information. Some of the factors that could cause actual results or outcomes to differ materially from the results expressed, implied or forecasted by such forward-looking information, including some of the assumptions used in making such statements, are discussed more fully in Hydro One’s filings with the securities regulatory authorities in Canada, which are available on SEDAR+ at www.sedarplus.com. Hydro One does not intend, and it disclaims any obligation, to update any forward-looking information, except as required by law.

FAQ

What projects does Hydro One (HRNNF) describe in this 6-K filing?

Hydro One describes two major 500-kV transmission projects: the Northeast Power Line between Hanmer TS and Mississagi TS, and the Longwood to Lakeshore Transmission Line between Longwood TS and Lakeshore TS, both in Ontario, supporting regional electricity needs and economic activity.

How much will Hydro One’s new Ontario transmission lines cost?

The Northeast Power Line is planned as an approximately $1.8 billion transmission line, while the Longwood to Lakeshore Transmission Line represents an approximately $1.2 billion investment. These figures reflect planned capital costs for constructing the single-circuit 500-kV lines in Ontario.

What extra electricity capacity will Hydro One’s new lines provide?

The Northeast Power Line is expected to increase transmission transfer capability between northeast and northwest Ontario by approximately 900 MW. The Longwood to Lakeshore Transmission Line is anticipated to bring about 550 MW of electricity to southwest Ontario to support jobs, agri-business and manufacturing.

When are Hydro One’s Northeast and Longwood–Lakeshore lines expected to be completed?

Construction of the approximately $1.8 billion Northeast Power Line is planned to be completed in 2029. The approximately $1.2 billion Longwood to Lakeshore Transmission Line is expected to be completed in 2030, subject to regulatory approvals and project execution.

How are First Nations involved in Hydro One’s new transmission projects?

Through Hydro One’s First Nation Equity Partnership Model, proximate First Nations will have the opportunity to invest in a 50 per cent equity stake in the transmission line component of each project. Hydro One and these First Nations will collaborate on planning, development and construction.

What scale of operations does Hydro One (HRNNF) highlight in this filing?

Hydro One highlights 1.5 million customers, $39.7 billion in assets as at December 31, 2025, and 2025 annual revenues of $9 billion. In 2025, it invested $3.4 billion in its networks and purchased $3.0 billion of goods and services.

Filing Exhibits & Attachments

1 document

Press Releases

• EX-99.1 EX-99.1 9.2 KB