ISG contacted Sacx to assist with the infrastructure and power upgrades for the Ministry of Justice Rapid Cell Deployment Program at HMP Rochester. The site was due to receive 80 modular cabins manufactured by Reds10 and would require anew 2.4MVA power supply to site.

What we did:

Sacx undertook site surveys and worked closely with the HMP Rochester FM Team, GFSL to understand the sites existing capacity, current loading and designed and developed an upgrade scheme in conjunction with UKPN.

The additional capacity required for the site resulted in the upgrade of the internal private HV Network including new Substation, RMU, Metering Unit, Transformer, and modifications to the HV wiring network. External upgrade and reinforcement work to the UKPN Network were also required to increase the site’s overall capacity.

This additional capacity required upgrades to the backup power and standby systems on site. Sacx designed and installed a new Standby Generator Solution including an independent 10,000l fuel tank, with auto transfer pumps. This ensured that in the event of a power outage or mains failure, power would be restored via the automatic start and operation of the backup generator.

All works were required to be completed without distribution to the HMP Rochester power supply allowing for HMP Rochester to operate as normal.

Challenges overcome:

Works were delivered around and in conjunction with the main ISG construction build and within an existing and live substation compound. Special care and attention was taken to ensure the works were completed while maintaining power to the site as normal, additional temporary generators were deployed to the site from our hire fleet allowing for Sacx to swap power generator from mains supplies to generators while upgrades were taking place and maintaining power supply.

The works also required numerous crane lifts and specialised transport to place the assets, some weighing over 14,000kg into their final position. These lifts were managed and conducted around live prison operations and in some cases required the lifting over numerous 5m fences.


The delivered scheme was completed on time and to budget and the detailed planning of network switching and backup generators resulted in works being completed without any power outages for the site.

Let the Numbers Speak

Electrical Supply
Construction Period
0 Weeks
Crane Lifts




Commercial, MOJ


Civil Engineering, Electrical


HMP Rochester


HV Upgrade and Backup Generator Installation




6 Week construction period
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