Potential Constrained Areas

Under the Market Rules (Chapter 7, Section 22.10), the IESO is provided discretion to designate one or more areas of the IESO-controlled grid as potential constrained area (PCA). Market Manual 14.1, Section 2.1 further specifies the process under which the IESO may designate PCAs.

The PCA designations are as follows:

PCA name

Element name and type

Publication date

PCA start date

PCA end date

CA_MMW_202512

Interface:

MMW

Resources:

CARIBOUFALLS-LT.AG123

EARFALLS-LT.AG1234

MANITOUFALLS-LT.AG12345

WHITEDOG-LT.AG123

December 1, 2025

January 15, 2026

N/A

CA_TWM_NEW_202512

Interface:

TWM_NEW

Resources:

ATIKOKAN-LT.G1

CARIBOUFALLS-LT.AG123

EARFALLS-LT.AG1234

MANITOUFALLS-LT.AG12345

WHITEDOG-LT.AG123

December 1, 2025

January 15, 2026

N/A

CA_BLIP_202512

Interface:

BLIP

Resources:

BRIGHTONCGS-LT.AG1-1B

BRIGHTONCGS-LT.G1A

EASTWCGS-LT.G1

EASTWCGS-LT.G2

PSU_GREENFIELD-LT.G1

PSU_GREENFIELD-LT.G2

PSU_GREENFIELD-LT.G3

PSU_GSPC-LT.G1

GSPC-LT.G3

LAUZON-LT.AG_EBUS

LAUZON-LT.AG_JBUS

LEAMINGTON-LT_GENSET

NELSONCHP2-LT.TG

STCLAIRCGS-LT.AG_T3

STCLAIRCGS-LT.AG_T4

TASARNIA-LT.G861

TASARNIA-LT.G871

TASARNIA-LT.G881

TASARNIA-LT.G891

TAWINDSOR-LT.AG12

TILBURYBESS-LT.BATT_TG1

TILBURYBESS-LT.BATT_TG2

WALKERBESS4-LT.BATT_TG

WALKERBESS5-LT.BATT_TG

WALKERBESS6-LT.BATT_TG

WESTWINDSOR-LT.AG12

December 1, 2025

January 15, 2026

N/A



Preliminary Analysis of Potential Constrained Areas (PCAs)

The IESO has performed a preliminary analysis of Potential Constrained Areas (PCAs) based on historical constraint data observed after the first three months of the new market launch. This information is made available as per the implementation plan. These PCAs are not an official designation and are posted below for informational purposes only. The official PCA designations will be made later this year.

PCA name

Element name and type

Publication date

PCA start date

PCA end date

CA_TWM_202508

Interface:

TWM

Resources:

ATIKOKAN-LT.G1

EARFALLS-LT.AG1234

MANITOUFALLS-LT.AG12345

WHITEDOG-LT.AG123

August 18, 2025

N/A

N/A

CA_BLIP_202508

Interface:

BLIP

Resources:

BELLERVRWF-LT.AG_T1

BRIGHTONCGS-LT.G1A

DILLON-LT.AG_T1

EASTLAKESCWF-LT.AG_T1

EASTWCGS-LT.G1

EASTWCGS-LT.G2

ERIEAU-LT.AG_T1

GOSFIELD-LT.AG_T1

LANDONWF-LT.AG_T1

NELSONCHP2-LT.TG

NKENT1WF-LT.AG_T1

PAROCHES-LT.AG_T1

PTBURWELL-LT.AG1

RAILBEDWF-LT.AG_SR

SILVERCRKSF-LT.AG_T1

SPENCECGS-LT.AG_T1

STCLAIRCGS-LT.AG_T3

STCLAIRCGS-LT.AG_T4

TASARNIA-LT.G861

TASARNIA-LT.G871

TASARNIA-LT.G881

TASARNIA-LT.G891

TAWINDSOR-LT.AG12

WALKERBESS4-LT.BATT_TG

WALKERBESS5-LT.BATT_TG

WALKERBESS6-LT.BATT_TG

WINDSORSF-LT.AG_T1

August 18, 2025

N/A

N/A