Tpl-008-1

TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

A. Introduction
1.

Title:

Transmission System Planning Performance Requirements for Extreme
Temperature Events

2.

Number:

TPL-008-1

3.

Purpose:

Establish Transmission system planning performance requirements to
develop a Bulk Power System (BPS) that will operate reliably during
extreme heat and extreme cold temperature events.

4.

Applicability:
4.1. Functional Entities:
4.1.1. Transmission Planner
4.1.2. Planning Coordinator

5.

Effective Date: See Implementation Plan for Project 2023-07.

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TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

B. Requirements and Measures
R1. Each Planning Coordinator shall identify, in conjunction with its Transmission
Planner(s), each entity’s individual and joint responsibilities for completing the
Extreme Temperature Assessment, which shall include each of the responsibilities
described in Requirements R2 through R11. Each responsible entity shall complete its
responsibilities such that the Extreme Temperature Assessment is completed at least
once every five calendar years. [Violation Risk Factor: Lower] [Time Horizon: Long-term
Planning]
M1. Each Planning Coordinator, in conjunction with its Transmission Planner(s), shall
provide dated documentation of each entity’s individual and joint responsibilities,
such as meeting minutes, agreements, copies of procedures, or protocols in effect
between entities or between departments of a vertically integrated system, or email
correspondence that identifies an agreement has been reached on individual and joint
responsibilities for completing the Extreme Temperature Assessment, and that these
responsibilities were completed such that the Extreme Temperature Assessment was
completed once every five calendar years.
R2. Each Planning Coordinator shall identify the zone(s) to which the Planning Coordinator
belongs to under Attachment 1 and shall coordinate with all Planning Coordinators
within each of its identified zone(s), to identify one common extreme heat benchmark
temperature event and one common extreme cold benchmark temperature event for
each of its identified zone(s) when completing the Extreme Temperature Assessment.
The benchmark temperature events shall be obtained from the benchmark library
maintained by the ERO or developed by the Planning Coordinators. Each benchmark
temperature event identified by the Planning Coordinators shall: [Violation Risk
Factor: High] [Time Horizon: Long-term Planning]
2.1. Consider no less than a 40-year period of temperature data ending no more than
five years prior to the time the benchmark temperature events are selected; and
2.2. Represent one of the 20 most extreme temperature conditions based on the
three-day rolling average of daily maximum (heat) or daily minimum (cold)
temperature across the zone.
M2. Each Planning Coordinator shall have evidence in either electronic or hard copy format
that it identified the zone(s) to which it belongs to, under Attachment 1, and that it
coordinated with all other Planning Coordinators within each of its identified zone(s)
to identify one common extreme heat benchmark temperature event and one
common extreme cold benchmark temperature event meeting the criteria of
Requirement R2 for each of their identified zone(s) when completing the Extreme
Temperature Assessment.
R3. Each Planning Coordinator shall coordinate with all Planning Coordinators within each
of its zone(s) identified in Requirement R2, to implement a process for developing
benchmark planning cases for the Extreme Temperature Assessment that represent
the benchmark temperature events selected in Requirement R2 and sensitivity cases to
demonstrate the impact of changes to the basic assumptions used in the benchmark

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TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

planning cases. This process shall include the following: [Violation Risk Factor: Medium]
[Time Horizon: Long-term Planning]
3.1. Selection of System models within the Long-Term Transmission Planning Horizon
to form the basis for the benchmark planning cases.
3.2. Forecasted seasonal and temperature dependent adjustments for Load,
generation, Transmission, and transfers within the zone.
3.3. Assumed seasonal and temperature dependent adjustments for Load,
generation, Transmission, and transfers in areas outside the zone, as needed.
3.4. Identification of changes to at least one of the following conditions for sensitivity
cases: generation, real and reactive forecasted Load, or transfers.
M3. Each Planning Coordinator shall have dated evidence that it implemented a process
for coordinating the development of benchmark planning cases and sensitivity cases
for the Extreme Temperature Assessment as specified in Requirement R3.
R4. Each responsible entity, as identified in Requirement R1, shall use the process
developed in Requirement R3 and data consistent with that provided in accordance
with the MOD-032 standard, supplemented by other sources as needed, to develop
the following and establish category P0 as the normal System condition in Table 1:
[Violation Risk Factor: High] [Time Horizon: Long-term Planning]
4.1. One common extreme heat and one common extreme cold benchmark planning
case.
4.2. One common extreme heat and one common extreme cold sensitivity case.
M4. Each responsible entity, as identified in Requirement R1, shall have dated evidence in
either electronic or hard copy format that it developed benchmark planning cases and
sensitivity cases in accordance with Requirement R4.
R5. Each responsible entity, as identified in Requirement R1, shall have criteria for
acceptable System steady state voltage limits and post-Contingency voltage deviations
for completing the Extreme Temperature Assessment. [Violation Risk Factor: Medium]
[Time Horizon: Long-term Planning]
M5. Each responsible entity, as identified in Requirement R1, shall provide dated evidence,
such as electronic or hard copies of the documentation, specifying the criteria for
acceptable System steady state voltage limits and post-Contingency voltage deviations
for completing the Extreme Temperature Assessment.
R6. Each responsible entity, as identified in Requirement R1, shall define and document
the criteria or methodology to be used in the Extreme Temperature Assessment to
identify instability, uncontrolled separation, or Cascading within an Interconnection.
[Violation Risk Factor: High] [Time Horizon: Long-term Planning]
M6. Each responsible entity, as identified in Requirement R1, shall provide dated evidence,
such as electronic or hard copies of documentation, specifying the criteria or
methodology to be used in the Extreme Temperature Assessment to identify instability,
uncontrolled separation, or Cascading within an Interconnection in accordance with
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TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

Requirement R6.
R7. Each responsible entity, as identified in Requirement R1, shall identify the
Contingencies for each category in Table 1 that are expected to produce more severe
System impacts on its portion of the Bulk Electric System. The rationale for those
Contingencies selected for evaluation shall be available as supporting information.
[Violation Risk Factor: Medium] [Time Horizon: Long-term Planning]
M7. Each responsible entity, as identified in Requirement R1, shall provide dated evidence,
such as electronic or hard copies of documentation, of the Contingencies for each
category in Table 1 that are expected to produce more severe System impacts on its
portion of the Bulk Electric System along with supporting rationale.
R8. Each responsible entity, as identified in Requirement R1, shall complete steady state
and transient stability analyses in the Extreme Temperature Assessment using the
Contingencies identified in Requirement R7, and shall document the assumptions and
results. Steady state and transient stability analyses shall be performed for the
following: [Violation Risk Factor: High] [Time Horizon: Long-term Planning]
8.1. Benchmark planning cases developed in accordance with Requirement R4 Part
4.1.
8.2. Sensitivity cases developed in accordance with Requirement R4 Part 4.2.
M8. Each responsible entity, as identified in Requirement R1, shall provide dated evidence,
such as electronic or hard copies of documentation, of the assumptions and results of
the steady state and transient stability analyses completed in the Extreme
Temperature Assessment.
R9. Each responsible entity, as identified in Requirement R1, shall develop a Corrective
Action Plan(s) when the analysis of a benchmark planning case, in accordance with
Requirement R8 Part 8.1, indicates its portion of the Bulk Electric System is unable to
meet performance requirements for category P0 or P1 in Table 1. For each Corrective
Action Plan, the responsible entity shall: [Violation Risk Factor: High] [Time Horizon:
Long-term Planning]
9.1. Document alternative(s) considered when Non-Consequential Load Loss is
utilized as an element of a Corrective Action Plan for a Table 1 P1 Contingency.
9.2. Be permitted to utilize Non-Consequential Load Loss as an interim solution,
which normally is not permitted for category P0 in Table 1 for situations that are
beyond the control of the Planning Coordinator or Transmission Planner that
prevent the implementation of a Corrective Action Plan in the required
timeframe, provided that the responsible entity documents the situation causing
the problem, alternatives evaluated, and takes actions to resolve the situation.
9.3. Make its Corrective Action Plan available to, and solicit feedback from, applicable
regulatory authorities or governing bodies responsible for retail electric service
issues.
9.4. Be permitted to have revisions to the Corrective Action Plan in subsequent
Extreme Temperature Assessments, provided that the planned Bulk Electric
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TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

System shall continue to meet the performance requirements of Table 1.
M9. Each responsible entity, as identified in Requirement R1, shall provide dated evidence,
such as electronic or hard copies of documentation, of each Corrective Action Plan
developed in accordance with Requirement R9 when the analysis of a benchmark
planning case indicates its portion of the Bulk Electric System is unable to meet
performance requirements for category P0 or P1 in Table 1. Evidence shall include
documentation of correspondence with applicable regulatory authorities or governing
bodies responsible for retail electric service issues and any revision history.
R10. Each responsible entity, as identified in Requirement R1, shall evaluate and document
possible actions designed to reduce the likelihood or mitigate the consequences and
adverse impacts of the event(s) if analyses conclude there could be instability,
uncontrolled separation, or Cascading within an Interconnection, for the following:
[Violation Risk Factor: Lower] [Time Horizon: Long-term Planning]
10.1. Table 1 P7 Contingencies in benchmark planning cases analyzed in accordance
with Requirement R8 Part 8.1.
10.2. Categories P0, P1, and P7 in Table 1 in sensitivity cases analyzed in accordance
with Requirement R8 Part 8.2.
M10. Each responsible entity, as identified in Requirement R1, shall provide dated evidence,
such as electronic or hard copies of documentation that it evaluated and documented
possible actions designed to reduce the likelihood or mitigate the consequences and
adverse impacts when the analyses conclude there could be instability, uncontrolled
separation, or Cascading within an Interconnection for Table 1 P7 Contingencies in
benchmark planning cases or categories P0, P1, or P7 in Table 1 in sensitivity cases.
R11. Each responsible entity, as identified in Requirement R1, shall provide its Extreme
Temperature Assessment results within 60 calendar days of a request to any
functional entity that has a reliability related need and submits a written request for
the information. [Violation Risk Factor: Medium] [Time Horizon: Long-term Planning]
M11. Each responsible entity, as identified in Requirement R1, shall provide dated evidence,
such as email notices, documentation of updated web pages, or postal receipts
showing recipient, that it provided its Extreme Temperature Assessment to any
functional entity who has a reliability need within 60 calendar days of a written request.

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TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

C. Compliance
1.

Compliance Monitoring Process
1.1. Compliance Enforcement Authority: “Compliance Enforcement Authority”
means NERC or the Regional Entity in their respective roles of monitoring and
enforcing compliance with the NERC Reliability Standards.
1.2. Evidence Retention: The following evidence retention period(s) identify the
period of time an entity is required to retain specific evidence to demonstrate
compliance. For instances where the evidence retention period specified below
is shorter than the time since the last audit, the Compliance Enforcement
Authority may ask an entity to provide other evidence to show that it was
compliant for the full-time period since the last audit.
The applicable entity shall keep data or evidence to show compliance as
identified below unless directed by its Compliance Enforcement Authority to
retain specific evidence for a longer period of time as part of an investigation.
•

Each responsible entity shall retain evidence of compliance with each
requirement in this standard for five calendar years or one complete
Extreme Temperature Assessment cycle, whichever is longer.

1.3. Compliance Monitoring and Enforcement Program: “Compliance Monitoring
Enforcement Program” or “CMEP” means, depending on the context (1) the
NERC Compliance Monitoring and Enforcement Program (Appendix 4C to the
NERC Rules of Procedure) or the Commission-approved program of a Regional
Entity, as applicable, or (2) the program, department or organization within
NERC or a Regional Entity that is responsible for performing compliance
monitoring and enforcement activities with respect to Registered Entities’
compliance with Reliability Standards.

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TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

Table 1 – Steady State & Stability Performance Events
Steady State & Stability:
a. Instability, uncontrolled separation, or Cascading within an Interconnection, defined in accordance with Requirement R6,
shall not occur.
b. Consequential Load Loss as well as generation loss is acceptable as a consequence of any event excluding P0.
c. Simulate the removal of all elements that Protection Systems and other controls are expected to automatically disconnect
for each event.
d. Simulate Normal Clearing unless otherwise specified.
e. Planned System adjustments such as Transmission configuration changes and re-dispatch of generation are allowed if such
adjustments are executable within the time duration applicable to the Facility Ratings.
Steady State Only:
f. Applicable Facility Ratings shall not be exceeded.
g. System steady state voltages and post-Contingency voltage deviations shall meet the criteria identified in Requirement R5.

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TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

Table 1 – Steady State & Stability Performance Events

Category

P0
No
Contingency

Initial
Condition

Normal
System

Event1

None

Fault Contingency
Type3
BES Level

N/A

Interruption
of Firm
Transmission
Service
Allowed

Non-Consequential Load Loss
Allowed
Benchmark
Sensitivity Cases
Planning Cases

N/A

Yes

No6

Yes

≥ 200 kV

Yes

Yes6

Yes

Yes

Yes

Yes

Loss of one of the following:
1. Generator
P1
Single
Contingency

Normal
System

2. Transmission Circuit
3. Transformer2
4. Shunt Device4
5. Single Pole of a DC line

SLG

The loss of:

P7
Multiple
Contingency
(Common
Structure)

3Ø

Normal
System

1. Any two adjacent (vertically
or horizontally) circuits on
common structure5

SLG

≥ 200 kV

2. Loss of a bipolar DC line

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TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

Table 1 – Steady State & Stability Performance Events
1. If the event analyzed involves BES elements at multiple System voltage levels, the lowest System voltage level of the
element(s) removed for the analyzed event determines the BES level of the event. For P7 events, the BES level of the event is
the highest System voltage level of the element(s) removed for the analyzed event.
2. For non-generator step up transformer outage events, the reference voltage, as used in footnote 1, applies to the low-side
winding (excluding tertiary windings). For generator and Generator Step Up transformer outage events, the reference
voltage applies to the BES connected voltage (high-side of the Generator Step Up transformer). Requirements which are
applicable to transformers also apply to variable frequency transformers and phase shifting transformers.
3. Unless specified otherwise, simulate Normal Clearing of faults. Single line to ground (SLG) or three-phase (3Ø) are the fault
types that must be evaluated in Stability simulations for the event described. A 3Ø or a double line to ground fault study
indicating the criteria are being met is sufficient evidence that a SLG condition would also meet the criteria.
4. Requirements which are applicable to shunt devices also apply to FACTS devices that are connected to ground.
5. Excludes circuits that share a common structure for 1 mile or less.
6. Benchmark planning cases require the development of a Corrective Action Plan when the responsible entity’s portion of the
BES is unable to meet the performance requirements for categories P0 or P1. Additionally, in benchmark planning cases,
Non-Consequential Load Loss is not permitted for category P0 except where permitted as an interim solution in a Corrective
Action Plan in accordance with Requirement R9 Part 9.2.

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TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

Violation Severity Levels
Violation Severity Levels
R#

Lower VSL

Moderate VSL

High VSL

Severe VSL

R1.

The responsible entity
completed its individual and
joint responsibilities such that
the Extreme Temperature
Assessment was completed,
but it was completed less than
or equal to six months late.

The responsible entity
completed its individual and
joint responsibilities such that
the Extreme Temperature
Assessment was completed,
but it was completed more
than six months but less than
or equal to 12 months late.

The responsible entity
completed its individual and
joint responsibilities such that
the Extreme Temperature
Assessment was completed,
but it was completed more
than 12 months but less than
or equal to 18 months late.

The Planning Coordinator, in
conjunction with its
Transmission Planner(s), failed
to identify individual and joint
responsibilities for completing
the Extreme Temperature
Assessment.
OR
The responsible entity
completed its individual and
joint responsibilities such that
the Extreme Temperature
Assessment was completed,
but it was completed more
than 18 months late.

R2.

N/A

N/A

The Planning Coordinator
coordinated with all Planning
Coordinators within each
identified zone to identify one
common extreme heat and
one common extreme cold
benchmark temperature event
for completing the Extreme
Temperature Assessment, but
one of the identified events
failed to meet all the criteria of
Requirement R2.

The Planning Coordinator
coordinated with all Planning
Coordinators within each
identified zone to identify one
common extreme heat and
one common extreme cold
benchmark temperature event
for completing the Extreme
Temperature Assessment, but
both of the identified events
failed to meet all of the criteria
of Requirement R2.
OR
The Planning Coordinator failed

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TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

Violation Severity Levels
R#

Lower VSL

Moderate VSL

High VSL

Severe VSL
to coordinate with all Planning
Coordinators within each
identified zone to identify one
common extreme heat and one
common extreme cold
benchmark temperature event
for completing the Extreme
Temperature Assessment.

R3.

N/A

N/A

N/A

The Planning Coordinator did
not coordinate with all
Planning Coordinators within
each of its identified zone(s) to
implement a process for
developing benchmark
planning cases.
OR
The Planning Coordinator
coordinated with all Planning
Coordinators within each of its
identified zone(s) to
implement a process for
developing benchmark
planning cases, but the
process did not include all of
the required elements.

R4.

N/A

N/A

N/A

The responsible entity, as
identified in Requirement R1,
did not use the process
developed in Requirement R3
to develop benchmark
planning cases or sensitivity
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TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

Violation Severity Levels
R#

Lower VSL

Moderate VSL

High VSL

Severe VSL
cases.
OR
The responsible entity, as
identified in Requirement R1,
used the process developed in
Requirement R3 to develop
benchmark planning cases and
sensitivity cases, but did not
use data consistent with that
provided in accordance with
the MOD-032 standard,
supplemented by other
sources as needed, for one or
more of the required cases.
OR
The responsible entity, as
identified in Requirement R1,
used the process developed in
Requirement R3 and data
consistent with that provided
in accordance with the MOD032 standard, supplemented
as needed, but failed to
develop one or more of the
required planning or sensitivity
cases.

R5.

N/A

N/A

N/A

The responsible entity, as
identified in Requirement R1,
did not have criteria for
acceptable System steady
state voltage limits and postPage 12 of 20

TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

Violation Severity Levels
R#

Lower VSL

Moderate VSL

High VSL

Severe VSL
Contingency voltage
deviations for completing the
Extreme Temperature
Assessment.

R6.

N/A

N/A

N/A

The responsible entity, as
identified in Requirement R1,
failed to define or document
the criteria or methodology to
be used in the Extreme
Temperature Assessment to
identify instability,
uncontrolled separation, or
Cascading within an
Interconnection.

R7.

N/A

N/A

The responsible entity, as
identified in Requirement R1,
identified Contingencies for
each category in Table 1 that
are expected to produce more
severe System impacts on its
portion of the Bulk Electric
System, but did not include
the rationale for those
Contingencies selected for
evaluation as supporting
information.

The responsible entity, as
identified in Requirement R1,
did not identify Contingencies
for each category in Table 1
that are expected to produce
more severe System impacts
on its portion of the Bulk
Electric System.

R8.

The responsible entity, as
identified in Requirement R1,
completed steady state and
transient stability analyses in

The responsible entity, as
identified in Requirement R1,
completed steady state and
transient stability analyses in

The responsible entity, as
identified in Requirement R1,
completed steady state and
transient stability analyses in

The responsible entity, as
identified in Requirement R1,
completed steady state and
transient stability analyses in

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TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

Violation Severity Levels
R#

R9.

Lower VSL

Moderate VSL

High VSL

Severe VSL

the Extreme Temperature
Assessment using the
Contingencies identified in
Requirement R7, but failed to
document the assumptions for
one or more sensitivity cases in
accordance with Requirement
R8.

the Extreme Temperature
Assessment using the
Contingencies identified in
Requirement R7, but failed to
document the assumptions for
one or more benchmark
planning cases in accordance
with Requirement R8.

the Extreme Temperature
Assessment using the
Contingencies identified in
Requirement R7, but failed to
document results for one or
more of the sensitivity cases in
accordance with Requirement
R8.

the Extreme Temperature
Assessment using the
Contingencies identified in
Requirement R7, but failed to
document results for one or
more of the benchmark
planning cases in accordance
with Requirement R8.
OR
The responsible entity, as
identified in Requirement R1,
failed to complete steady state
or transient stability analyses
and document results in the
Extreme Temperature
Assessment using the
Contingencies identified in
Requirement R7, in accordance
with Requirement R8.

N/A

N/A

The responsible entity, as
identified in Requirement R1,
developed a Corrective Action
Plan in accordance with
Requirement R9, but failed to
make its Corrective Action
Plan available to, or solicit
feedback from, applicable
regulatory authorities or
governing bodies responsible
for retail electric service
issues.

The responsible entity, as
identified in Requirement R1,
failed to develop a Corrective
Action Plan when the
benchmark planning case study
results indicate the System is
unable to meet performance
requirements for the Table 1 P0
or P1 Contingencies.
OR
The responsible entity, as
identified in Requirement R1,
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TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

Violation Severity Levels
R#

Lower VSL

Moderate VSL

High VSL

Severe VSL
developed a Corrective Action
Plan, but it was missing one or
more of the elements of
Requirement R9 Part 9.1, 9.3
and 9.4 (as applicable).

R10.

N/A

N/A

The responsible entity, as
identified in Requirement R1,
evaluated and documented
possible actions to reduce the
likelihood or mitigate the
consequences and adverse
impacts of the event(s) when
analyses conclude there could
be instability, uncontrolled
separation, or Cascading
within an Interconnection
where required under
Requirement R10 Part 10.1,
but failed to evaluate and
document possible actions
where required under
Requirement R10 Part 10.2.

The responsible entity, as
identified in Requirement R1,
evaluated and documented
possible actions to reduce the
likelihood or mitigate the
consequences and adverse
impacts of the event(s) when
analyses conclude there could
be instability, uncontrolled
separation, or Cascading
within an Interconnection
where required under
Requirement R10 Part 10.2,
but failed to evaluate and
document possible actions
where required under
Requirement R10 Part 10.1.
OR
The responsible entity, as
identified in Requirement R1,
failed to evaluate and
document possible actions to
reduce the likelihood or
mitigate the consequences and
adverse impacts of the event(s)
when analyses conclude there

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TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

Violation Severity Levels
R#

Lower VSL

Moderate VSL

High VSL

Severe VSL
could be instability,
uncontrolled separation, or
Cascading within an
Interconnection where required
under Requirement R10 Parts
10.1 and 10.2.

R11.

The responsible entity, as
identified in Requirement R1,
provided its Extreme
Temperature Assessment
results to functional entities
having a reliability related need
who requested the information
in writing, but it was more than
60 days but less than or equal
to 80 days following the
request.

The responsible entity, as
identified in Requirement R1,
provided its Extreme
Temperature Assessment
results to functional entities
having a reliability related need
who requested the information
in writing, but it was more than
80 days but less than or equal to
100 days following the request.

The responsible entity, as
identified in Requirement R1,
provided its Extreme
Temperature Assessment
results to functional entities
having a reliability related
need who requested the
information in writing, but it
was more than 100 days but
less than or equal to 120 days
following the request.

The responsible entity, as
identified in Requirement R1,
provided its Extreme
Temperature Assessment
results to functional entities
having a reliability related
need who requested the
information in writing, but it
was more than 120 days
following the request.
OR
The responsible entity, as
identified in Requirement R1,
did not provide its Extreme
Temperature Assessment
results to functional entities
having a reliability related
need who submitted a written
request for the information.

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TPL-008-1 – Transmission System Planning Performance Requirements for Extreme Temperature Events

D. Regional Variances
None.

E. Associated Documents
•

Implementation Plan for Project 2023-07

•

Technical Rationale Document

•

Consideration of Issues and Directives for FERC Order 896.

•

ERO Benchmark Event Library

•

TPL-008 Data Library Read Me

Version History
Version
1

Date
12/10/2024

Action
Adopted by the NERC Board of Trustees

Change
Tracking
Addressing FERC
Order 896

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TPL-008-1 Supplemental Material

Attachment 1: Extreme Temperature Assessment Zones

The table below lists the zones to be used in the Extreme Temperature Assessment and
identifies the Planning Coordinators that belong to each zone. In accordance with Requirement
R2, each Planning Coordinator is required to identify the zone(s) to which it belongs. Planning
Coordinators, in different zones within a broader planning region, may use the same
benchmark temperature events for their respective benchmark planning cases, provided the
benchmark temperature events meet the criteria of Requirement R2 for each zone.
Eastern Interconnection
Zone
MISO North

Planning Coordinator(s) in MISO that serve portions of MISO in Montana, North
Dakota, South Dakota, Minnesota, Iowa, Wisconsin, Michigan, Indiana, Illinois,
Missouri, and Kentucky

MISO South

Planning Coordinator(s) in MISO that serve portions of Arkansas, Mississippi,
Louisiana, and Texas

SPP North

Planning Coordinator(s) in portions of SPP that serve Iowa, Montana, Nebraska,
North Dakota, and South Dakota.

SPP South

Planning Coordinator(s) in portions of SPP that serve Arkansas, Kansas, Louisiana,
Missouri, New Mexico, Oklahoma, and Texas.

PJM

Planning Coordinator(s) that serves PJM

New England

Planning Coordinator(s) in NPCC that serve the six New England States

New York

Planning Coordinator(s) in NPCC that serve New York

SERC

Planning Coordinator(s) in SERC, excluding those that serve Florida and those in
MISO, SPP, and PJM

Florida

Planning Coordinator(s) in SERC that serve Florida

Central Canada

Planning Coordinator(s) that serve Saskatchewan and Manitoba region of MRO

Ontario

Planning Coordinator(s) in NPCC that serve Ontario

Maritimes

Planning Coordinator(s) in NPCC that primarily serve New Brunswick, Nova Scotia,
Prince Edward Island, and Northern Maine

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TPL-008-1 Supplemental Material

Western Interconnection
Zone
Southwest

Planning Coordinator(s) in the Southwest region of WECC, including El Paso in
West Texas

Pacific Northwest Planning Coordinator(s) in the Pacific Northwest region of WECC
Great Basin

Planning Coordinator(s) in the Great Basin region of WECC

Rocky Mountain

Planning Coordinator(s) in the Rocky Mountain region of WECC

California/Mexico Planning Coordinator(s) in the California/Mexico region of WECC
Western Canada

Planning Coordinator(s) that primarily serve British Columbia and Alberta region of
WECC
ERCOT Interconnection

Zone
ERCOT

Planning Coordinator(s) in Texas that are part of the ERCOT Interconnection
Quebec Interconnection

Zone
Quebec

Planning Coordinator(s) that serve Quebec in the NPCC Region.

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TPL-008-1 Supplemental Material

The map below depicts an approximation of the zones to be used in the Extreme Temperature
Assessment and is provided as a visual aid; to the extent that there is a conflict between the
map and the table, the table controls. This map is not to be used for compliance purposes.
TPL-008-1 Weather Zones Map

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