HMP Grendon fire safety infrastructure upgrade
In 2021 Vinci asked SJD to provide a £2.5m electrical upgrade for a major fire safety infrastructure project at HMP Grendon in Buckinghamshire.
HMP Grendon is a specialist therapeutic prison with capacity for 300 prisoners, currently housing around 180 men. The prison is seen throughout the world as a benchmark for good practice in helping to rehabilitate offenders and prepare them for release. The well-maintained facilities are seen to play a key role in the success of the prison.
With full responsibility for the design, the project involved updating the electrical infrastructure for ancillary buildings, corridors, kitchens, the chapel, gymnasia and administration offices, but the main bulk of the works were carried out in six prisoner wings.
The wings accommodate between 32-42 cells and SJD was given access to one wing at a time with the prisoners being decanted elsewhere during the works.
SJD partially rewired each cell block providing containment, cabling and distribution for power, lighting, general alarm and fire alarm systems. The project also included the specialist wiring for the smoke extractor system and night sanitation system which enables prisoners access to toilets during the night. A high-pressure misting system was installed for fire safety with all installations having failsafe systems for back-up power. SJD was also asked to design and supply bespoke in-cell security cappings for the smoke detectors and misting nozzles. These were manufactured of steel and powder coated.
SJD isolated and stripped out the failing central battery emergency lighting system and undertook the full design and installation of new lighting within each corridor, landing and side rooms with a self-test system.
Work in corridors also included designing a bespoke night light control system which automatically switched to night light mode and a new general alarm system, and phase failure indicators with load shedding of non-essential supplies. Back-up generators to accommodate essential supplies for the fire safety system were installed and upgrades made to the mains infrastructure.
The building was originally constructed in the 1960s and the challenge was to devise a method of containing the new electrical services, to include mounting of the new light fittings, smoke detection system and housing the pipework and misting heads for the sprinkler misting system. SJD designed a bespoke ceiling mounted multi-compartment trunking system, which was manufactured specifically for the project.
Glenn Spilsbury, Vinci Facilities’ senior site manager at HMP Grendon has worked closely with SJD for four years. He said: “SJD have been exemplary and one of the best electrical contractors I’ve worked with. The project has run very smoothly, and any unforeseen problems have been dealt with easily. SJD will solve any difficulties, often backed up with drawings, and find solutions.”
He added: “They are decent tradespeople, and the workmanship has been very good. We work to a weekly programme with weekly progress meetings and SJD always meet their deadlines. They’re used to working in prisons and they’ve made it very easy for me.”
“The project has run very smoothly….. SJD have made it very easy for me.”
Trish Bradley, regional supply chain manager at Vinci Facilities explained the importance of contractors being sensitive to their surroundings. She said: “We need to be able to rely on our contractors to understand the difficulties in working in prison settings. They are unique sites that have many rules and procedures that must be adhered to and there are extra security steps to take for every project, so our contractors must have patience and a flexible approach to their work.
“We need contractors who we can work collaboratively with and trust to keep to the programme to deliver high quality installations for our clients. That’s why our long-term partnership with SJD works so well.”
Other projects for Vinci include work at HMP Woodhill, which is a men’s high security prison and young offender institution in Milton Keynes, operated by His Majesty’s Prison Service.
The prison needed a contractor which could prove it had experience in the sector and would be compliant and accredited to deliver this type of sensitive infrastructure work. SJD carried out design amendments, fire and security improvements there including power, diverse supplies and emergency lighting valued at over £3m during a three-year period from 2018.
In 2022, SJD undertook the electrical design and refurbishment of the gatehouse at HMP Pentonville under a £1.2m contract, this project was followed by the detailed design for fire safety improvements and a roof repair at HMYOI Feltham.
Work at HMP Grendon is expected to be completed in early 2026.
