Data centre electrical design

Data centre electrical design decides how power reaches every rack, what keeps it there when the utility fails, and how much of the system can be maintained without shutting anything down. We design the electrical side of data centres, server rooms and network rooms, from the service and generator through the UPS to the power strips in the racks.

A data centre is a small building with a very large, very steady load that cannot tolerate even a short interruption. That changes the priorities. A normal office can ride out a blackout; a server room loses data and services in the time it takes a breaker to trip. The design has to answer three questions early: how much power the IT equipment will draw on day one and at full build-out, how much redundancy the business actually needs, and how the room will be maintained once it is running.

What we design and build

• Utility service and main switchgear sized for the IT load, cooling and building loads, with room for growth.
• Standby generators, automatic transfer switches and fuel arrangements for the runtime the business needs.
• UPS systems, battery systems and bypass arrangements, including modular UPS that grows with the load.
• Power distribution units, remote power panels, busway and branch circuits to the racks.
• Rack PDUs and A and B feeds for dual-corded equipment.
• Power for cooling: computer room air handlers, chillers, in-row units and pumps, and which of them need UPS or generator support.
• Grounding and bonding for the electrical system and the telecommunications equipment.
• Power monitoring, metering and alarms tied into a building automation or data centre management system.
• Supporting studies: load calculations, short-circuit, coordination and arc flash.

The diagram shows the shape most designs come back to: two separate paths from source to rack, so that losing or servicing one does not take the IT load down. Smaller rooms often have a single path with redundant components instead; the redundancy level is a business decision we make with you, not a default.

How it works

1. We start with why. We ask what the room supports, what an hour of downtime costs the business, how fast the IT load is expected to grow and whether the equipment is dual-corded. Those answers set the redundancy level and the size of the first phase.
2. Site survey. For an existing building we check the service, spare capacity in the switchgear, generator size and age, the condition of any existing UPS and batteries, and where new equipment, cable tray and conduit can go. We also look at cooling, because every kilowatt of IT load becomes heat that the mechanical system has to remove on the same backed-up power.
3. Design. We size the UPS, generator and distribution for the planned load, draw the single-line diagram, lay out the electrical room and the power distribution in the white space, and decide which loads sit on UPS, which on generator only, and which on utility only. The short-circuit and coordination studies make sure a fault in one rack opens the breaker closest to it and nothing upstream.
4. Permit drawings and tender. Drawings for permit are sealed by a licensed professional engineer where required. The specifications cover the UPS, batteries, generator, transfer equipment and PDUs in enough detail that bids can be compared on equal terms.
5. Construction. Installation is done by licensed electrical contractors under permit. We review shop drawings and equipment submittals, visit during construction and answer site questions.
6. Integrated testing and close-out. Each piece of equipment is started up by its supplier, then the whole system is tested together: utility failure, generator start and transfer, UPS on battery, return to utility, and maintenance bypass. Deficiencies are tracked to completion and the drawings are updated to show what was built.

What to have ready

• The IT load today and the expected load at full build-out, even as a range.
• A list of racks and how many are dual-corded.
• Existing single-line diagrams, panel schedules, UPS and generator nameplate data.
• Recent maintenance reports for the UPS, batteries and generator.
• Any availability targets the business has committed to, internally or to customers.

Designing for growth

Most data centres start well below their final load. Building the whole electrical system on day one ties up money in equipment that runs lightly loaded for years, and lightly loaded UPS systems are less efficient. A phased design installs the switchgear, pathways and space for the full build-out, then adds UPS modules, PDUs and generator capacity as the load grows.

What you get

A sealed permit set where required, with a single-line diagram that shows every source, UPS, PDU and transfer path, electrical room and white space layouts, equipment schedules, panel schedules and specifications. You also get the calculations behind them: the load calculation, UPS and battery sizing, generator sizing, and the short-circuit, coordination and arc flash studies.

Just as useful is a written description of how the system behaves: what happens when the utility fails, what each bypass is for, and which breakers can be opened for maintenance without dropping load. That document is what operations staff reach for at two in the morning.

Who it's for

• Owners building a new data centre or computer room.
• IT and facility managers whose server room has outgrown its UPS or its circuits.
• Organisations moving from a single-path room to dual-path power.
• Colocation and edge sites adding capacity in phases.
• Architects and general contractors who need an electrical engineer for a data centre project.

For the electrical side in more depth, read our guides on N, N+1 and 2N redundancy, the data centre power chain and rack PDUs and power monitoring. If you need the whole room, including cabling, racks and cooling, see data centre design and build.

Common questions