Anyone planning to construct a new connection to, or planning to modify an existing connection to the IESO-controlled grid is required to complete the Connection Assessment and Approvals (CAA) process.  This IESO process assesses the impact of new or modified connections on the reliability of the integrated power system. It also identifies any changes to the connection proposal or enhancements to the transmission system required to mitigate any potential adverse impact.


The CAA process applies to:

  • Generation facilities
  • Embedded generation facilities greater than 10 MW
  • Transmission facilities
  • Load facilities or a one-time addition of load greater than 10 MW
  • Ancillary services, such as frequency control, black start capability, voltage control, reactive power, operating reserve, etc.

​Obtaining an Assessment

Applicants connecting to a transmission system should first consult with the applicable transmitter for advice regarding the preferred point of connection. This is especially important in situations where:

  • System constraints may influence the connection
  • New equipment is required to be installed within transmitter-owned facilities

Applicants connecting to a transmission system or distributors applying for connection assessment on behalf of their customers must have a detailed project design in place before beginning the CAA process.

Renewable energy project applicants must have an executed contract prior to beginning the CAA process.​

If the connection applicant wishes to transfer a project to another party, the original connection applicant and the new connection applicant are required to execute an asset transfer agreement with the IESO. All three parties (the original connection applicant, the buyer/assignee and the IESO) must sign the agreement. Please contact the IESO at Connection.Assessments@ieso.ca for more details on how to transfer a project to another party.

System Impact Assessment

A System Impact Assessment (SIA) is a mandatory assessment conducted by the IESO to assess the impact of the connection proposal on the reliability of the integrated power system. SIAs are conducted with input from the affected transmitter(s) and in consultation with the connection applicant.

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Expedited System Impact Assessment

An expedited SIA, which only requires a simply study, is conducted when the connection proposal does not represent a major system change and is not expected to have a major impact on the reliability of the integrated power system. The IESO determines whether an SIA or expedited SIA is appropriate.

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Feasibility Study (Optional)

Before conducting a SIA, connection applicants may request an optional Feasibility Study. This is to determine the technical acceptability of a new or modified connection to the IESO-controlled grid and to identify alternate connection options.

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Application Status

Connection proposals are located on a project list containing status information for assessments and links to the completed SIA reports.

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