Wellington, July 6 NZPA - Vector has started to build a 150km fibre optic network connecting national grid operator Transpower's 14 Auckland substations.

The project, to be operational by the end of 2010, is part of Transpower's national grid upgrade.

Vector chief executive Simon Mackenzie said the network would reinforce Transpower's communications technology that monitored and controlled the flow of electricity between substations.