April 5, 2023

Prior To Major Event

1. Did the distributor have any prior warning that the Major Event would occur?

Yes, Environment Canada issued a Special Weather Statement on April 4th, 2023 stating prolonged freezing rain leading to 10 to 15 millimetres of ice accretion was forecasted.

2. If the distributor did have prior warning, did the distributor arrange to have extra employees on duty or on standby prior to the Major Event beginning? Brief description of arrangements, or explain why extra employees were not arranged.

Hydro Ottawa had all of its employees on standby and on-site during the onset of the event. In addition, Hydro Ottawa had a full complement of on-shift personnel, a full on-call roster of field technicians and management personnel working overnight.

3. If the distributor did have prior warning, did the distributor issue any media announcements to the public warning of possible outages resulting from the pending Major event?

Yes, Hydro Ottawa published media announcements across social channels warning of possible outages resulting from the pending Major event.

4. Did the distributor train its staff on the response plans for a Major Event? 

Yes. Hydro Ottawa has an established Electrical Emergency Response Plan and Organization, which includes processes and procedures for which staff are trained on.  Formal training is completed annually according to Market Rules.  In addition, weekly preparation meetings are held to refresh on-call management personnel.

During the Major Event

1. Please identify the main contributing Cause of the Major Event as per the table in section of the Electricity Reporting and Record Keeping Requirements.

  • Loss of Supply
  • Lightning
  • Adverse Weather - Wind
  • Adverse Weather - Snow
  • Adverse Weather - Freezing Rain/Ice Storm
  • Adverse Environment - Fire
  • Adverse Environment - Flooding
  • Others

1.1. Please provide a brief description of the event (i.e. what happened?).

On April 5th at 7:26 PM, Hydro One M31A transfer tripped. Which resulted in a loss of supply to two Hydro Ottawa substations leading to 25,303 Hydro Ottawa customer outages.

2. Was the IEEE Standard 1366 used to identify the scope of the Major Event? If not, why not?

Yes. Hydro Ottawa used the IEEE Standard 1366.

3. When did the Major Event begin (date and time)? 

April 5, 2023 at 10:54 AM

4. Did the distributor issue any information about this Major Event, such as estimated times of restoration, to the public during the Major Event? If yes, please provide a brief description of the information. If no, please explain.

Once available, estimated times of restoration were provided through proactive communications via website, news releases, press conference, updates to the shareholder, email to customers and social media outlets. ETRs were also provided while responding to requests for information from the following audiences: customer enquiries, media, shareholder.

5. How many customers were interrupted during the Major Event? What percentage of the distributor’s total customer base did the interrupted customers represent?

163,448 customers were interrupted during the Major Event, representing 45% of Hydro Ottawa’s total customer base.

6. How many hours did it take to restore 90% of the customers who were interrupted?

The major damage from the storm started April 5th at 10:54 AM and 90% of customers were restored by April 7th at 3:25 AM

7. Were there any outages associated with Loss of Supply during the Major Event? If so, please report on the duration and frequency of Loss of Supply outages.

Yes, there were two outages due to Loss of Supply during the Major Event. One which resulted from a cable fault on the transmission supply and affected 25,303 customers for a total of 29,978 customer hours. This outage contributed 0.069 to SAIFI and 0.083 to SAIDI. The second loss of supply affected 726 customers for a total of 3,787 customer hours.

8. In responding to the Major Event, did the distributor utilize assistance through a third party mutual assistance agreement with other utilities? If yes, please provide the name of the utilities who provided the assistance?

Burlington Hydro, London Hydro, ERTH Power

9. Did the distributor run out of any needed equipment or materials during the Major Event? If so, please describe the shortages.


After the Major Event

1. What steps, if any, are being taken to be prepared for or mitigate such Major Events in the future (i.e., staff training, process improvements, system upgrades)?

  • No further action is required at this time.
  • Additional staff training
  • Process improvements
  • System upgrades
  • Others

Additional comments:

Hydro Ottawa will conduct a debrief to discuss lessons learned from the Major Event. Process improvements from those lessons learned will be implemented for future major events.

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