The Energy Blog £17m new primary substation is successfully ‘switched on’

St Helier West is now delivering power to homes and businesses

Jersey Electricity’s new £17m primary substation, St Helier West, (SHW) is now successfully delivering power to homes and businesses in and around town. The facility, which has been almost 10 years in the planning and building, was ‘energised’ last week and, after being left ‘on soak’ for 24 hours, JE engineers completed the switching work which joined SHW to the existing 90kV network and brought it into operation.

JE CEO Chris Ambler described the facility as one of the most important infrastructure assets in the Island and praised the engineers whose skills and commitment have brought the project to fruition on schedule for winter 2018/19. He said: ‘St Helier West is the final piece in the jigsaw of our robust 90kV network ring. It relieves pressure on supplies to 80 percent of St Helier – around 13,000 customers previously served by Esplanade and Queen’s Road primaries. It further enhances supply security and also future proofs the network to meet the increasing demand for low carbon electricity. I thank our project team and all our contractors who have worked so hard to bring this project to a successful conclusion.

‘Though the station is now in service, much work remains to be done on the outside where we will be investing a significant amount in covering the façade in granite to blend in with the surrounding area. Further landscaping with shrubs and trees will be planted and a public viewing platform overlooking St Aubin’s Bay will be incorporated and completed next year. Our objective is to leave the site in better condition than we found it.’

Project and Asset Manager Mark Vivian said it had been one of the most challenging infrastructure builds JE had ever undertaken and described the ‘switch on’ as ‘the culmination of many hours of work by JE staff and contractors, which required careful co-ordination over the past three years.’ 

The 10,000 sq ft steeply sloping site at Westmount was a former coastal quarry requiring extensive ground investigations throughout 2015 before complex civils works could begin. These involved the removal of 27,000 tons of material, including 5,000 tons of rock, piling to support the building slab and the erection of a new retaining wall to protect the facility. Local firm Jayen completed this work in September 2017 and handed the site to specialist French contractors Engie INEO to undertake the actual build that took a year. In recent months, the substation has been equipped with transformers from Italy, control systems from the UK and cabling from Belgium.

SHW is one of five primary substations that play a critical role in transforming the voltage from 90,000 Volts (90kV) at which electricity is transmitted from France down to 11,000 Volts (11kV).  These facilities subsequently distribute the energy across the network, matching supply and demand at all levels in the system. JE’s 787 smaller substations transform the voltage further from 11,000 Volts down to 400 Volts and 230 Volts for use in homes and businesses.