Overview of the Connection Process

Connection Assessment - Timeline


Prepare Application Obtain Approval Design and Build Authorize Market and Program Participation Register Equipment Commission Equipment and Validate Performance

The process to connect a new facility or to modify an existing facility involves up to six stages as described below. A detailed diagram is available here.

New or modified connections to a transmitter’s system are generally subject to all six stages, while new or modified connections to a distributor’s system may only be subject to the first three.

You are required to successfully complete all applicable stages to receive final approval to connect your new or modified facility to the electricity system and begin commercial operation.

The entire process can take anywhere from a few months for small modifications to existing facilities, to more than three years for major modifications or to connect new facilities.


Existing and potential market participants that are developing plans for future new or modified connections are strongly encouraged to get involved in the IESO’s regional  planning process which is intended to prepare the electricity system to meet future needs. By engaging in the process, your organization will be better informed, which could mitigate some of the potential risks that the new or modified connection will trigger significant upgrades to the existing system. Subscribe to receive information about engagement opportunities for your region.

Explore your options with a technical feasibility study

Whether your organization is an existing or potential market participant, you can explore  options for a new or modified connection with the IESO’s technical feasibility study. (TFS). This optional, confidential service is provided on a cost-recovery basis to identify and mitigate potential issues with various connection options, and help participants select a final connection option. Once you chose your connection option, your facility will be ready to begin the connection process.

1.  Prepare application

Planned connection of new facilities and modifications to existing facilities must be assessed to identify and mitigate any potential adverse effect on the reliability of the electricity grid and its existing customers. To ensure that the applicable processes are initiated, as a first step, please contact your transmitter or distributor.

2.  Obtain conditional approval to connect

Your organization is required to obtain conditional approval for new or modified connections through the appropriate processes. Successful completion of the connection assessment process results in a conditional approval to connect. This stage typically takes one year.

Transmission system connections

New connections or modifications to facilities connected to a transmitter’s system are subject to the IESO's system impact assessment (SIA) and the transmitter's customer impact assessment (CIA).

If you are modifying your existing facility to permit the connection of a new facility within its premises, then you as owner of the host facility are responsible to initiate the SIA and CIA processes.

Contact the IESO Connection Assessments at connection.assessments@ieso.ca for more information.

Distribution system connections

New connections or modifications to facilities connected to a distributor’s system must participate in the distributor’s connection assessment process. As part of this process, distributors may need to participate in the IESO’s and transmitter’s connection assessment processes to obtain their conditional approval to connect on your behalf. 

3.  Design and build

The detailed design and build of your new or modified facility must consider the requirements for connection identified by the conditional approval to connect. Any modification from the preliminary design not covered by the conditional approval needs to be brought to the attention of the party that issued the approval to determine if a re-assessment is required.

If you are connecting a new facility or modifying an existing facility that is connected to a distributor’s system, and have no intention or obligation to become a market participant, your distributor will guide you through the rest of their process and connect your new or modified facility to their distribution system. If necessary, the distributor will obtain the IESO’s final approval to connect on your behalf.

The timing for this stage ranges from 18 to 36 months.

 The following stages must be completed if your organization:

  • Is a market participant modifying an existing facility
  • Seeks to connect a new facility to a transmitter’s system
  • Intends to participate in the IESO-administered markets

Please contact the IESO Market Registration at market.registration@ieso.ca to initiate stages 4 to 6.

4.  Authorize market and program participation

To participate in the IESO-controlled grid, IESO-administered markets or programs, you must register your organization with the IESO to authorize it as a market or program participant. This stage typically takes about one month.

5.  Register equipment

The equipment, telemetry, and metering installed at your facility must be registered and tested with the IESO. The IESO uses the data provided by market participants for the systems and models that are necessary to maintain the reliability of the IESO-controlled grid and to operate the IESO-administered markets. This stage takes at least three months.

6.  Commission equipment and validate performance

The IESO may require commissioning tests of your equipment to validate its models and data and ensure compliance with reliability standards, as outlined in the applicable market manuals and the conditional approval for connection. During this stage, specific tests required by the IESO must be completed to demonstrate that the equipment installed at your facility meets applicable performance requirements. This stage typically takes at least three months.


Successful completion of all six stages, to the satisfaction of the IESO, is required to obtain final approval to connect to the IESO-controlled grid, and start commercial operation in the IESO-administered markets.