GMP has over 972 miles of transmission lines, and about 190 substations across the state. The majority of GMP’s transmission lines are operated at both 34.5 kV and 46 kV, with a small portion at 69 kV. GMP utilizes two Control Rooms which are completely redundant with each other if needed. The Control Rooms are staffed 24 hours a day and in addition to operating the transmission system and associated substations, they operate 32 power production sites and oversee distribution tie circuits along with all aspects of daily service restoration. The Control Area coordinates with Vermont Electric Power Company, better known as VELCO, the state’s transmission company. They also coordinate with ISO New England, a regional transmission organization that monitors and ensures New England’s constant power supply.
Open Access Transmission Information
On Feb. 1, 2005, ISO New England and participating transmission owners implemented a Regional Transmission Organization (RTO) governed by ISO New England FERC Electric Tariff No. 3 – Section II Open Access Transmission Tariff (RTO OATT). The RTO OATT superseded the OATT’s of all Participating Transmission Owners. The RTO OATT covers transmission service on all network facilities including pool transmission facilities and the Highgate Converter Facilities.
All transmission service types are briefly explained in the ISO New England matrix (see Transmission Service Types), which also contains application information.
OASIS: Registration information for access to the New England Open Access Same Time Information System (OASIS) may be found via:
Registration information
Regional Network Service: Open access to integrate all resources to the regional network load is provided under Schedule 9, Regional Network Service of the RTO OATT. Application for Regional Network Service must be made to ISO New England.
- Schedule 9 (See Section II Open Access Transmission Tariff)
Through or Out Service: Open access to utilize the Highgate Converter Facilities is provided under Schedule 8 Through or Out Service of the RTO OATT. Application for Through or Out Service must be made to ISO New England. Call Bruce Kay at ISO New England at 413-535-4062 for more information.
- Schedule 8 (See Section II Open Access Transmission Tariff)
Local Network or Point-to-Point Service: Open access to the GMP transmission system is provided under Schedule 21 – Common (common provisions applicable to local service from all local service providers) and Schedule 21 – GMP (provisions applicable to local service from GMP) of the RTO OATT. Application for firm or non-firm point-to-point transmission service over the GMP transmission system must be made to ISO New England. See the link below for a blank application. Call (888) 835-4672 for more information.
- Schedule 21
- Schedule 21- GMP
- Schedule 21 Firm and/or Non-Firm Point-to-Point Transmission Service over the GMP transmission system: Point-to- Point Application
- ATC Mathematical Algorithms
Pursuant to Schedule 21 GMP, no later than October 15, GMP must post an annual forecast of non-binding cost estimates for the next service year, and no later than June 15, GMP must post an annual true-up. Any modifications to the Annual True-up and/or Material Accounting Changes resulting from an Informal Challenge to the Annual True-up also must be posted on the GMP website. The Annual Forecast, Annual True-up and any modifications to the Annual True-up and/or Material Accounting Changes can be accessed via the Green Mountain Power OASIS webpage link at the bottom of this page.
Phase I/II HVDC Service: Open access to the GMP portion of the Phase I/II HVDC transmission facilities is provided under Schedule 20A‚ Point-to-Point Service over the Phase I/II HVDC Transmission Facilities and Schedule 20A of the RTO OATT. Application for firm or non-firm point-to-point transmission service over the GMP portion of the Phase I/II HVDC transmission facilities must be made to GMP. See the link below for a blank application. Call (888) 835-4672 for more information.
- Schedule 20A-Common
- Schedule 20A-GMP
- Application for Firm and/or Non-Firm Point-to-Point Transmission Service over the GMP portion of the Phase I/II HVDC transmission facilities
- Form of Phase I/II HVDC-TF Service Agreement
- Form of Phase I/II Service Agreement for the Resale, Reassignment or Transfer of Point to Point Phase I/II HVDC-TF Service
Large Generator Interconnection: Large generator interconnections (over 20 MW) with the GMP transmission system are governed by Schedule 22‚ Standard Large Generator Interconnection Procedures of the RTO OATT. A request for interconnection with the GMP transmission system must be made to ISO New England. Call Dave Forrest at ISO New England at 413-540-4584 for more information.
Small Generator Interconnection: Small generator interconnections (20 MW and under) with the GMP transmission system are governed by Schedule 23, Standard Small Generator Interconnection Procedures of the RTO OATT. A request for interconnection with the GMP transmission system must be made to ISO New England. Call Dave Forrest at ISO New England at 413-540-4584 for more information.
Interconnection with GMP Distribution System: A request for interconnection with the GMP distribution system may be made to GMP by calling GMP’s Engineering Department at 1-888-835-4672.
GMP Links:
FERC Order 2004 Standards of Conduct Information and other GMP OASIS related information can be found using the following link:
For customers with an OASIS digital certificate please use the following link: