National Grid has a variety of tools available to assist it in performing system balancing role, including: buying or selling electricity in the Balancing Mechanism, purchasing ancillary services and other services.

The Balancing Mechanism provides a means of adjusting the level of production or consumption of individual generators or demands. The parties which are bound by the terms of the Balancing Settlement Code (BSC) and actively participate into Balancing Mechanism are referred to Balancing Mechanism Unit (BMU).They are generally the holders of generation, transmission, distribution and supply licences. Whilst traders and others (e.g. Large loads who reduce their electricity consumption) may choose to become parties to the Code, they are referred to as Non-BMU.

As a rough guide, the table below shows which category of providers can potentially provide which services, subject to the specified requirements being fulfilled (details of which are given in this Pack).

For each service, details are given on Balancing Services Adjustment Data (BSAD) and Applicable Balancing Services Volume Data (ABSVD). BSAD is used in the calculation of Energy Imbalance Prices, i.e. where applicable the costs (or part of the costs) of the service are used in the calculation of Energy Imbalance Prices.  ABSVD is used for the purposes of determining a providers Imbalance Volumes, in general Balancing Services, deemed to be Applicable will be those services required by the System Operator for economic operation of the transmission system, that result in the service provider being exposed to imbalance charges whilst assisting in system balancing.