In the US, we are involved in electricity transmission and our principal activities are as follows:
Electricity transmission owner: We own and operate an electricity transmission network of approximately 13,800 kilometres spanning upstate New York, Massachusetts, Rhode Island, New Hampshire and Vermont. Our US electricity transmission facilities operate at voltages ranging from 69 kV to 345 kV, utilising nearly 13,700 kilometres of overhead line, nearly 140 kilometres of underground cable and 524 substations. We are the largest electricity transmission service provider in New England and New York by reference to the length of these high voltage transmission lines.
Canadian interconnector: We own and operate a 224 kilometre direct current transmission line rated at 450 kV that is a key section of an interconnector between New England and Canada.
As one of several transmission owners, we work with two distinct independent system operators in New England and New York. These non profit system operator entities for New England and New York are responsible for operating organised wholesale markets for energy, for operating reserves and capacity, for maintaining the operating reliability of the New England and New York networks, for coordinating the activities of the transmission owners, and for managing transparent transmission expansion planning processes.
The transmission owners are responsible for certain aspects of the operation of the facilities they each own, such as maintenance, equipment restoration and switching operations.
National Grid also works closely with the independent system operators in New England and New York to support efficient market and network operations and transmission investment.