Hydro One Limited — Proxy Solicitation & Information Statement 2023

May 3, 2023

PROXY FORM

Annual Meeting Hydro One Limited

WHEN: Friday, June 2, 2023 at 9:30 am EDT

WHERE:

In person: Lakehead University Advanced Technology & Academic Centre 955 Oliver Rd Thunder Bay, ON P7B 5E1 Virtual: www.virtualshareholdermeeting.com/HRNNF2023

STEP 1

REVIEW YOUR VOTING OPTIONS

ONLINE: VOTE AT PROXYVOTE.COM USING YOUR COMPUTER OR MOBILE DATA DEVICE. YOUR CONTROL NUMBER IS LOCATED BELOW.

BY TELEPHONE: YOU MAY ENTER YOUR VOTING INSTRUCTIONS BY TELEPHONE AT: ENGLISH: 1-800-474-7493 OR FRENCH: 1-800-474-7501 BY MAIL: THIS PROXY FORM MAY BE RETURNED BY MAIL IN THE ENVELOPE PROVIDED.

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SCAN TO VIEW MATERIAL AND VOTE NOW

REMINDER: PLEASE REVIEW THE MANAGEMENT INFORMATION CIRCULAR BEFORE VOTING.

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CONTROL NO.: ➔

PROXY DEPOSIT DATE: May 31, 2023 at 9:30 am EDT

The control number has been assigned to you to identify your shares for voting.

You must keep your control number confidential and not disclose it to others other than when you vote using one of the voting options set out on this form. Should you send this form or provide your control number to others, you are responsible for any subsequent voting of, or subsequent inability to vote, your shares.

INSTRUCTIONS:

1. This Form of Proxy is solicited by and on behalf of management of the issuer.

2. You have the right to appoint a person, who need not be a shareholder, other than the person(s) specified on the other side of this form to represent you at the Virtual Annual Meeting of Shareholders of Hydro One Limited. If you wish to appoint a person (a proxyholder) other than the persons whose names are printed on the other side of this form (management proxyholders) then you must:

3. Write the name of your proxyholder on the “Appointee” line and provide a unique EIGHT (8) CHARACTER APPOINTEE IDENTIFICATION NUMBER (used for your proxyholder to access the Virtual Meeting) in the space provided on the other side of this form, sign and date the form, and return it by mail, or

4. Go to ProxyVote.com and insert the name of your proxyholder in the “Change Appointee(s)” section and provide a unique EIGHT (8) CHARACTER APPOINTEE IDENTIFICATION NUMBER on the voting site (used for your proxyholder to access the Virtual Meeting).

5. In order for your proxyholder to access the Virtual Meeting, you MUST provide your proxyholder the EXACT NAME and EIGHT (8) CHARACTER APPOINTEE IDENTIFICATION NUMBER . Proxyholders can only be validated at the Meeting using the EXACT NAME and EIGHT (8) CHARACTER APPOINTEE IDENTIFICATION NUMBER you enter.

IF YOU DO NOT PROVIDE THE EXACT NAME AND CREATE AN EIGHT (8) CHARACTER APPOINTEE IDENTIFICATION NUMBER AND PROVIDE IT TO YOUR APPOINTEE, YOUR PROXYHOLDER WILL NOT BE ABLE TO ACCESS THE VIRTUAL MEETING.

1. This Form of Proxy confers discretionary authority to vote on amendments or variations to the matters identified in the notice of the Meeting and with respect to any new matters that may properly be brought before the Meeting or any adjournment or postponement thereof.

2. This Form of Proxy will not be valid and not be acted upon or voted unless it is completed and delivered as outlined herein.

3. If the shares are registered in the name of more than one owner (for example, joint ownership, trustees, executors, etc.), then all those registered should sign this Form of Proxy. If you are voting on behalf of a corporation or another individual, documentation evidencing your power to sign this Form of Proxy with signing capacity stated may be required.

4. In order to expedite your vote, you may use the Internet or a touch-tone telephone, and entering the control number noted above. The telephone system cannot be used if you designate a proxyholder (other than the management proxyholders) to represent you at the Virtual Meeting.

If you vote by Internet or telephone, do not mail back this Form of Proxy.

1. If the Form of Proxy is not dated, it will be deemed to bear the date on which it was mailed to the shareholder.

2. The shares represented by this form of proxy will be voted as directed. If no voting preferences are indicated on the reverse, the management proxyholders will vote as recommended by management.

3. Unless prohibited by law or you instruct otherwise, your proxyholder will have full authority to access and represent you at the Virtual Meeting, and present matters to the Virtual Meeting and any adjournment or postponement thereof, and vote on all matters that are brought before the Virtual Meeting or any adjournment or postponement thereof, even if these matters are not set out in this form or in the management information circular.

4. If these voting instructions are given on behalf of a body corporate, set out the full legal name of the body corporate, and the name and position of the person giving voting instructions on behalf of the body corporate.

5. If the items listed in the management information circular are different from the items listed on the other side of this form, the management information circular will be considered correct.

6. This Form of Proxy should be read in conjunction with the accompanying management information circular.

PLEASE SEE OVER

PROXY FORM Hydro One Limited

MEETING TYPE: Annual Meeting MEETING DATE: Friday, June 2, 2023 at 9:30 am EDT RECORD DATE: April 21, 2023 PROXY DEPOSIT DATE: May 31, 2023 at 9:30 am EDT CUID: ACCOUNT NO: CUSIP:

CONTROL NO.: ➔

STEP 2

APPOINT A PROXY (OPTIONAL)

APPOINTEE(S): David Lebeter or failing him, Chris Lopez

Change Appointee

If you wish to designate another person (other than the management proxyholders specified above) to access and represent you as your proxyholder at the Virtual Meeting, or any adjournment or postponement thereof, go to www.proxyvote.com or print your name or the name of the other person attending the Virtual Meeting in the space provided herein and provide a unique EIGHT (8) CHARACTER APPOINTEE IDENTIFICATION NUMBER USING ALL BOXES for your proxyholder to access the Virtual Meeting. You may choose to direct how your proxyholder shall vote on matters that may come before the Virtual Meeting or any adjournment or postponement thereof. Unless you instruct otherwise your proxyholder will have full authority to attend, vote, and otherwise act in respect of all matters that may come before the Virtual Meeting or any adjournment or postponement thereof, even if these matters are not set out in the proxy form or the management information circular for the Virtual Meeting. You can also change your proxyholder online at www.proxyvote.com.

You MUST provide your Proxyholder the EXACT NAME and an EIGHT (8) CHARACTER APPOINTEE IDENTIFICATION NUMBER to access the Virtual Meeting. Proxyholders can only access the Virtual Meeting using the EXACT NAME and EIGHT (8) CHARACTER APPOINTEE IDENTIFICATION NUMBER you enter below.

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PLEASE PRINT PROXYHOLDER NAME INSIDE THE BOX

MAXIMUM 22 CHARACTERS - PLEASE PRINT CLEARLY

➔

CREATE AN EIGHT (8) CHARACTER IDENTIFICATION NUMBER FOR YOUR PROXYHOLDER

MUST BE EIGHT CHARACTERS IN LENGTH - PLEASE PRINT CLEARLY

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STEP 3

COMPLETE YOUR VOTING DIRECTIONS

VOTING RECOMMENDATIONS ARE INDICATED BY OVER THE BOXES (FILL HIGHLIGHTED TEXT ITEM(S):	IN ONLY ONE BOX “		” PER ITEM IN BLACK OR BLUE INK)
FOR FOR WITHHOLD FOR WITHHOLD FOR WITHHOLD FOR WITHHOLD FOR WITHHOLD FOR WITHHOLD FOR WITHHOLD FOR WITHHOLD Election of Director: David Hay 1B Election of Director: Timothy Hodgson 1C Election of Director: David Lebeter 1D Election of Director: Mitch Panciuk 1E Election of Director: Mark Podlasly 1F Election of Director: Stacey Mowbray 1G Election of Director: Helga Reidel 1H Election of Director: Melissa Sonberg 1I Election of Director: Brian Vaasjo 1J Election of Director: Cherie Brant 1A FOR WITHHOLD WITHHOLD Election of Directors	THIS DOCUMENT MUST BE SIGNED AND DATED STEP 4 M M D D Y Y SIGNATURE(S) INVALID IF NOT SIGNED FOR WITHHOLD FOR WITHHOLD Election of Director: Susan Wolburgh Jenah 1K Appointment of External Auditors Appoint KPMG LLP as external auditors for the ensuing year and authorize the directors to fix their remuneration. 02 Say on Pay Advisory resolution on Hydro One Limited’s approach to executive compensation. 03 FOR AGAINST