The St Helier West substation, which serves 13,000 homes, was turned on in December 2018 and since then JE has worked with landscaping contractors to complete the exterior of the site.
The last few shrubs and sections of fencing will be in place shortly, enabling the 10,000sq-ft site to be cleared and allowing access to a public viewing platform above the building.
The disused quarry was first put forward in 2009 as one of six possible sites for the substation, which was needed to reinforce the network serving the north, south and west of St Helier. The sale of the land by the parish to JE for £250,000 was approved in November 2013.
After site investigation and an environmental impact assessment, local contractor Jayen began work at the start of 2016. The project involved excavation to a depth of up to 15 metres and the removal of 27,000 tons of material, including 5,000 tons of rock, and the erection of a new retaining wall.
Engie INEO, a specialist contractor from France, began building the substation in September 2017. Two transformers, manufactured by Tironi in Italy, were hoisted into position in March of the following year and the power was switched on a week before Christmas in 2018.
St Helier West is one of five primary substations that play a critical role in transforming the voltage from 90,000 volts – the level at which electricity is imported from France down to 11,000 volts. Energy is subsequently distributed across the network, matching supply and demand at all levels in the system. The Island has 787 smaller substations which transform the voltage down further from 11,000 volts to 400 and 230 volts for use in homes and businesses.
The new substation provides scope for future increases in demand, potentially for another 40 years. Since being switched on, the maximum demand has been 17 megawatts – the capacity is 40 megawatts. The project also helps give the Island greater resilience in terms of the security of supply. UK customers have an average of 78 minutes without power annually, compared with six minutes in Jersey.
