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Data centre substations: design from the ground up

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To ensure long-term flexibility, reliability and security, data centre operators are increasingly looking to build, own and operate their own substations.

These can be supplied and built by specialist companies who have expertise in the connection to the distribution network operator (DNO) and who understand the particular needs of data centre operators.

However, designing substations for data centres can often involve unique civil engineering challenges and specialist cable routing knowledge, which is why it’s imperative to call in the experts in these disciplines from the outset of a project.

Why own and operate your own substation?

Data centre operators are finding that there may be advantages in specifying and owning their own substation. It may be built sooner than one from a utility company. You’re more likely to be able to decide exactly what type of substation you want which can help influence the budget. You’ll be able to future-proof your substation by building in flexibility and scalability, and perhaps alternative greener/cheaper sources of power generation. You can decide on the level of protection you want from a range of threats such as deliberate acts of vandalism, extreme weather events or other environmental impacts.

Most data centre operators will subcontract the design and build of substations, and often their ongoing operation and maintenance, to specialist supply companies.

What’s in a design?

Designing substations involves particular challenges such as providing cable-pulling calculations, assessing substation structures for blast loading resistance against fault situation events, and providing AutoTrack analysis and modelling to demonstrate how large equipment – such as transformers – will be moved into position on site.

Some substation providers can handle these tasks themselves as they have the required in-house resource. Others, however, may prefer to bring in design specialists, alleviating risk to programme and costs.

What are the risks?

Linking a data centre to the grid via a substation may require hundreds of metres of HV cabling. These bespoke cables can weigh up to 20-30kg per metre and usually can’t just be laid in the ground; routes must be pre-determined, and ducts and pulling pits designed. By providing precise cable routing designs and cable-pulling calculations it ensures that, when a cable is required to negotiate a bend, the pulling force doesn’t compromise the cable or the side wall of the duct. Either of these situations could result in programme delays and huge unplanned costs, should any of the elements be damaged and need replacing.

Whilst rare, electrical faults in high voltage equipment can potentially cause overpressures, which could damage the substation in which the equipment is housed. An arc fault in switchgear, for example, can cause sudden high temperatures. This heats the air around the equipment and emits a blast loading into the room. If the room has insufficient volumetric capacity, this rapid increase in volume has nowhere to go, potentially damaging the building.

Good design will assess whether the structure of the building can tolerate this overpressure. If not, then a blast duct can be designed to release overpressure from within a room via a louvre, discharging it into a safe space.

Typically, a substation will feature one or more transformers which can weigh 80-120 tonnes, or more, each. When these arrive on site it’s important to specify exactly how the transformer will be offloaded and put into position. An experienced design team will ensure this complex process is carried out seamlessly by carrying out Temporary Works designs and AutoTrack analysis to model the process before delivery day.

Other potential issues which can be foreseen and overcome by experienced substation designers include firewall requirements, noise, site constraints and environmental considerations. If a transformer is to be located close to another transformer or structure, a firewall may be required. If the site is close to a residential area, there could be disturbance from the low hum of a transformer. Good design can attenuate any potential noise issues.

How good design can reduce overall substation cost

Employing a specialist design company from the outset can reduce overall project time and cost. Some might see taking the time to undertake a thorough design process as a risk to programme timelines and budget but, in fact, the opposite is usually true.

Placing design firmly at the very centre of a substation projects doesn’t just save money – both in CapEx and whole life costs – it adds value, minimises risk and helps to create an asset which functions as intended long into the future.

The value of a trusted design team

A specialist design team will demonstrate a range of practices intended to deliver good value and prevent additional expense for a client during the procurement and operational life of a project.

These practices include early involvement which can design out problems from the start. Inevitably, as projects proceed, any redesigns have an impact on project time and cost. The earlier the design team’s engagement in a project, the more thorough the briefing process can be, reducing the chances of potentially costly redesigns later due to unforeseen factors.

Early briefing can also take into account any local authority planning considerations. Planning permission for a substation may be granted under ‘Permitted Development’ but in other cases may require a full planning application which demands more detailed drawings from the outset.

Employing a design team with agility and flexibility pays off. Using a company with this culture and attitude means they’re more likely to engage in new ideas which will yield project benefits in terms of time, cost and resources.

Experience has shown that, invariably, site visits positively impact project cost. Only so much design work can be achieved from behind a desk; new solutions, alternative ways of working and innovative ideas will often emerge from visits and discussions on site.

Design technology can offer cost savings while meeting the demands of the brief. For example, one way to enhance efficiency and precision is through technology such as innovative 3D and 4D modelling techniques to bring project benefits.

Collaborative relationships always have a positive impact on project efficiency, and can help achieve best value for clients through soft skills. This includes working closely with other client and project teams, refining the brief to solve problems more successfully: at a lower cost, using fewer resources or finishing sooner.


For any substation project it’s important to employ the correct design company with the right blend of experience, specialist skills and a wide range of work in different sectors. These projects often demand complex and detailed civil engineering design requirements, as well as strong knowledge of local authority planning regulations.

From tender stage to detailed design, experience and collaboration make a huge difference in how the civils design is optimised to identify and mitigate potential risks, recognise opportunities, and ensure successful project delivery.

Asa Whitfield

Managing Director of Whitfield Construction Services (WCS)

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