Milton Keynes University Hospital Critical Power Supplies

Project value:
Project Commenced:
March 2021
Project completed:
February 2022
Crown Commercial Services

About the project

The Enable Power Systems team at Enable Infrastructure (formerly BCM Construction) installed critical standby power generation equipment at Milton Keynes University Hospital (MKUH), upgrading the back-up power generation systems and local supplies that serve a large section of the hospital site.  

The project involved upgrading HV supplies and replacing the standby local generator in the existing substation to give the hospital a more robust electrical supply. The new 1400 kVA standby generator ensures that the dedicated medical professionals of MKUH can care for their patients without the threat of losing power to vital equipment during supply failures and outages at the Distribution Network Operator. 

The project was part of a seven-phase programme taking place over one year, with these works undertaken during the fifth phase. This was a key component of the MKUH’s decarbonisation and upgrade plan; it was, in fact, the final major item to be completed. The work also formed part of MKUH NHS Foundation Trust’s overall energy management and stabilisation planning. 

As the principal contractor, Enable Infrastructure were responsible both for the design and installation of the new equipment and for administering a temporary backup power supply to the hospital for the duration of the project. 

Our Enable Power Systems team drew deeply on their specialist knowledge to enable the phasing of the new equipment to ensure that essential supplies to the hospital were not disrupted at any point, so that both critical care and normal hospital working could continue throughout. 

Although impacted by the COVID-19 pandemic and market delays, by working collaboratively with the trust, Enable Infrastructure succeeded in delivering the project according to scope.   

“The successful completion of the project to upgrade substation 5&6, increasing the size of the transformers and standby generators to give greater resilience and provide increased capacity, supports the trust’s ambitious plans to significantly expand its hospital facilities through the delivery of a major capital works programme. In addition, the provision of new and refurbished buildings offers the opportunity ‘to lead where we can’ in developing, investing in, and applying the solutions required to decarbonise the MKUH estate.  

“Enable Infrastructure have executed the project to achieve a seamless transfer of power to the new infrastructure without any impact on the hospital’s 24-hour operations. They have shown that their experience of similar National Rail projects can be transferred to achieve the same high standards of installation.” 

Stuart Watson, Engineering Manager, BDP – MKUH Infrastructure Support 

Enable Infrastructure were awarded this work through the Crown Commercial Service (CCS) Framework, which enables public sector organisations and their arm’s-length bodies to secure building and civil engineering works projects. Specifically, this was from CCS, Lot 1.2 (Civil Engineering Works and Minor Associated Building Works – South England and Wales) and was awarded via the NHS. 

The project included phased decommissioning of two existing 500 kVA transformers. These were replaced with two new 1250kVA transformers, close-coupled with Lucy Electric 11kV ring main units. Two existing 350 kVA generators were replaced with a single (temporary) 1250kVA backup standby generator. In addition, an LV generator automatic changeover panel was installed, with capacity to allow for future site expansion.   

The new Cummins C1400D5 permanent standby generator is rated at 1400 kVA. For comparison, a standard UK home consumes 3Kva, which means this generator could power up to 460 homes at once! It was a ‘greener’ replacement for the existing pair of 350Kva generators. In addition, the upgrade future-proofed the hospital against a pending fuel levy increase on red diesel, since it allows the use of cleaner and more cost-effective HVO100 fuel instead. 

New HV and LV cabling was installed between the new equipment, including auxiliary supplies for battery chargers and heating systems for the generator, as well as 3-phase supplies for the fuelling systems.  

Civils works were required to enlarge the footprint of the existing substation so that it could accommodate one of the new transformers and to provide new cable duct routes. 

In the early design stages, it was found that the existing LV switchboard, which according to the scope was not being upgraded, could not take the fault ratings of the new transformers. We therefore held discussions with the client in order to arrive at an agreed working solution in the most cost-effective and practical way. 

The Enable Group made the calculations for the necessary crane lifts and oversaw the delivery and placements of the new equipment in February 2022. A 55-tonne mobile crane was used to deploy the external transformers and a 100-tonne mobile crane to install the genset. 

In line with our commitment to add social and community value wherever we operate, Enable Infrastructure carried out voluntary works in the new cancer ward patients’ garden. 

The challenge

  • Working on back-up and primary power supplies for an operational hospital for an extended period of time, with a requirement that there should be no loss of supply at any point in construction or during the supply change-over.  
  • Completing demolition works in a confined environment (a live back supply room) with the following hazards: HV power, LV power, standby generators, high-pressure fuel lines and fuel storage, water supplies and high-pressure gas mains into the boiler rooms.    
  • Working in a busy operational medical site during a pandemic, including using the main access roads to the delivery bays and mortuary, at a time when strict rules were in place to prevent the spread of COVID-19.  


The solution

  • Enable Infrastructure worked with the client to implement robust plans for back-up power throughout the project. This included running the hospital on the back-up generator system designed and installed by Enable Infrastructure. During the project, the standby power system successfully took over running the hospital power for several periods, with no interruption to service.  
  • Sequencing of works was implemented to maintain a safe working environment. The project was safely delivered, free of incidents.  
  • Enable Infrastructure implemented our own strict processes at all stages of the construction phase, maintaining hospital protocols and working according to the highest standards of professionalism to avoid any disruption to the hospital’s day-to-day running and to play our part in preventing the spread of the coronavirus.  

The deliverables

  • Site clearance and set-up 
  • Design, supply and building of the bunded transformer bases for the new substation 
  • Upgrade of the existing substation (SS 5-6) 
  • New trenching within the building to facilitate a GRP grid trench for air flow, as per cable design 
  • Phased decommissioning of the existing two 500 kVA transformers 
  • Installation of a temporary 1250 kVa generator to supply back-up power whilst the existing plant was upgraded 
  • Phased decommissioning of the two existing 350 kVA generators serving existing hospital supplies 
  • Increasing the substation footprint, including the construction of two transformer bases, to accommodate the new equipment 
  • Installation of compound earthing system works 
  • Construction of substation concrete base, including cable entry ducts and all cable ductwork 
  • Installation and commissioning of the new 1400 kVA standby replacement generator 
  • Installation of fuel polishing system and decommission of existing fuel supplies 
  • Supply and installation of control and protection equipment including battery charger, relays, RTUs, cabling and auxiliary wiring   
  • Supply & installation of HV cables, jointing and materials 
  • Supply & installation of HV and emergency tripping cables 
  • Reconfiguration of site lighting and emergency lighting, as well installation of new lighting within the substation compound. This included emergency lighting tests and supplying certification 
  • Supply of substation locks/access system. 

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