SPP revises minimum design standards for competitively bid transmission upgrades
Revision 4 of SPP's Minimum Transmission Design Standards adds 765 kV design information and other RFP-process changes, developed in consultation with Sargent & Lundy.
The document is titled 'Minimum Transmission Design Standards for Competitive Upgrades,' issued as Revision 4 dated 7/17/2026.1
SPP Staff revised the standards to Revision 4, dated 7/14/2026, to improve RFP processes and incorporate 765 kV information, in consultation with Sargent & Lundy.2
On the RFP process: SPP publishes a Request for Proposal for each Competitive Upgrade approved for construction by the SPP Board of Directors after January 1, 2015.3
Competitive Upgrades are subject to the Transmission Owner Selection Process set forth in Section III of Attachment Y of the SPP Open Access Transmission Tariff.4
Where the RFP and the design standards conflict, the RFP governs what the Respondent uses in its RFP Proposal, but where the RFP conflicts with the SPP Tariff or Business Practices, the Tariff and Business Practices govern.5
On ratings and clearance: the standards require transmission facility ratings to be established under NERC FAC-008 methodology and applicable FERC requirements, including FERC Order 881's ambient-adjusted ratings.6
The standards require a minimum design margin of 2 feet beyond NESC clearance requirements to account for survey and construction tolerances.7
On line and structure design: the standards require transmission lines rated 500 kV or higher and longer than 25 miles to include at least one complete transposition cycle unless studies demonstrate a non-transposed design meets SPP Planning Criteria.8
For structures exceeding approximately 92 feet, the standards require reduced shielding angles of less than 30 degrees, consistent with RUS Bulletin 1724E-200.9
Where a fiber communication path is required, the standards set a minimum of 48 fiber strands per cable.10
Coverage notes
Gridlight’s notes on what we looked for and did not find; these statements are Gridlight’s own and are not claim-checked against archived sources.
- The revision-history table gives earlier revisions (IR, 1, 2, 3) an explicit approval notation; the Revision 4 row in the excerpt carries no comparable note, so this piece does not state whether Revision 4 has cleared MOPC/PCWG approval.
- The document's title page is dated 7/17/2026 while the Revision 4 row in the revision-history table is dated 7/14/2026; the excerpt does not say which date is operative, and this piece does not resolve it.
- The materials do not identify which pending or upcoming SPP competitive-upgrade RFPs would be the first subject to the new 765 kV design requirements.
- The excerpt is truncated mid-Section 3.3.2 (Extreme Weather Events for substations); later material, including Section 4 on protection and control design, is not covered here.