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Operating Margins


National Grid Gas purchases Operating Margins ("OM") on an annual basis in line with both the requirements of TPD Section K of the UNC and obligations described in the National Grid Gas Safety Case in respect of the NTS (the "Safety Case"). The Safety Case places an obligation on National Grid Gas to maintain OM at levels and locations determined throughout the year.

The OM service is used to maintain system pressures in the period before other system management services become effective (e.g. national or locational balancing actions). Primarily, OM will be used in the immediate period following the occurrence of any of the following, to the extent that all other System Operator actions are insufficient:

(a) Supply Loss: Terminal, Sub-Terminal, Interconnector, LNG Importation Terminal

(b) Pipe Break (including loss of infrastructure that renders pipe unusable)

(c) Compressor Failure

(d) Demand Forecast Error.

A further quantity of OM is also procured to manage the orderly run-down of the system in the event of a Network Gas Supply Emergency (NGSE) whilst firm load shedding takes place.

For information on becoming an OM provider please contact Tahir Mahmood on +44 (0)1926 656005  or via e-mail