I size a prefabricated electrical building for a data center by starting with the electrical load, then converting that load into equipment, clearance, maintenance, safety, expansion, and site requirements. The building should accommodate the planned switchgear, transformers, UPS systems, batteries, generators or other electrical equipment while preserving safe access and future capacity. I also coordinate the design with the site, local regulations, utility requirements, fire strategy, transportation limits, and the installation sequence. A reliable size is therefore more than a floor-area estimate; it is the result of a coordinated electrical and physical layout.
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The first step is to establish the electrical capacity that the building must distribute, transform, protect, or support. I normally review the data center load study, utility information, single-line diagram, UPS architecture, generator arrangement, power factor assumptions, and redundancy objective. The design load should distinguish between current demand, design demand, and the capacity required after planned growth.
For three-phase systems, a basic apparent-power relationship is kVA = √3 × voltage × current ÷ 1,000. The final design still requires engineering review because transformer impedance, power factor, harmonics, fault levels, ambient conditions, and operating modes affect equipment selection. I avoid sizing the building from IT load alone, because cooling, lighting, controls, security, auxiliary systems, and electrical losses also consume space and power.
For example, a project may begin with a 2 MW IT load, but that figure does not by itself define the required transformer, UPS, switchgear, or battery-room footprint. The electrical schedule should identify the number and rating of each major item, such as 2,000 kVA transformers, 1,600 kVA UPS modules, or medium-voltage switchgear lineups. These values are illustrative planning inputs, not universal design requirements.
I use a detailed equipment schedule before calculating the building envelope. The schedule should include equipment tag, quantity, dimensions, weight, voltage, heat rejection, cable-entry direction, access requirements, and whether the equipment is indoor or outdoor rated. It should also identify which units operate together and which units require separation.
| Equipment or system | Information needed for sizing | Why it matters |
|---|---|---|
| MV or LV switchgear | Lineup length, depth, working clearance, cable access | Determines wall length, aisle width, and service routes |
| Transformers | Footprint, weight, heat output, separation, lifting method | Affects structural design, ventilation, and replacement access |
| UPS and batteries | Module dimensions, battery technology, heat, maintenance access | Influences room zoning, fire strategy, and environmental control |
| Control and auxiliary systems | Panel space, communications routes, lighting, HVAC, security | Prevents support systems from being added without planned space |
I also include spare sections, busway interfaces, cable termination zones, and temporary staging areas where the project requires them. A building that fits the equipment but cannot accept a replacement breaker or battery cabinet is not adequately sized. Equipment manufacturers’ installation instructions and the applicable electrical and fire requirements should control the final clearances.
After collecting the equipment data, I create a scaled layout rather than adding equipment dimensions together. The layout must show operating aisles, maintenance access, cable trenches or overhead routes, doors, partitions, emergency exits, lifting paths, and wall penetrations. I place equipment according to the single-line diagram and the actual sequence of power flow.
Working clearances are not optional spare space; they support safe inspection, testing, switching, and repair. The required clearance depends on voltage, equipment construction, local rules, and the manufacturer’s instructions, so I do not apply one generic aisle dimension to every project. As a practical coordination example, a 1.2 m maintenance aisle may be suitable for a particular low-voltage arrangement, but the governing requirement must be confirmed for the selected equipment and jurisdiction.
I distinguish between a normal operating aisle and a maintenance route. Maintenance may require doors to open fully, removable panels to be extracted, lifting equipment to enter, or a component to move out without dismantling adjacent equipment. This is especially important for transformers, UPS modules, battery cabinets, and large switchgear sections.
Electrical equipment converts part of its input power into heat, and batteries and power electronics may have specific temperature requirements. I request heat-loss data from each equipment manufacturer and use the combined result to coordinate HVAC, ventilation, louvers, filters, and controls. The building volume and wall arrangement may change when the project requires separate temperature zones.
The environmental design should consider outdoor temperature, humidity, dust, salt exposure, altitude, rain, snow, and the site’s maintenance practices. If the building is installed in a harsh environment, the enclosure, coating system, doors, cable entries, and ventilation strategy need to be selected accordingly. I use conservative assumptions until the project provides verified climate and equipment data.
Safety planning affects both the internal layout and the external footprint. I coordinate electrical separation, fire compartments, battery arrangements, emergency egress, arc-flash considerations, grounding, and equipment access with the project’s qualified engineers and authorities. A prefabricated electrical building should not be treated as an empty box into which equipment is placed after manufacturing.
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Cable routing frequently becomes a hidden source of added floor area. I identify incoming utility cables, transformer connections, generator feeders, UPS connections, control cables, grounding conductors, and communications routes before freezing the building dimensions. The design should show bend radii, termination space, trench depth, overhead supports, and separation between power and control wiring where required.
For example, a 600 mm cable trench is not automatically sufficient for every feeder arrangement; cable size, quantity, bending radius, heat dissipation, and termination details must be checked. Similarly, overhead routing may reduce floor congestion but can increase building height and affect transport. The best route depends on the equipment and site, not on a standard detail used without review.
Data center operators often plan phased growth, but the expansion method must be defined early. I ask whether future capacity will use spare switchgear sections, reserved transformer positions, additional UPS modules, a second building, or a separate electrical room. Each approach creates different requirements for foundations, cable routes, doors, structural loading, and temporary operation.
I recommend reserving space only when it has a defined function and installation path. Empty space without future cable provisions, spare bus connections, ventilation capacity, or access may not provide useful expansion. In many projects, a coordinated 10% physical allowance can be used as an initial planning placeholder, but the final allowance should follow the actual phasing strategy rather than an unsupported fixed percentage.
The largest possible internal layout may not be the best solution if the module cannot be transported, lifted, positioned, or serviced at the site. I verify road restrictions, maximum transport dimensions, crane capacity, turning radius, foundation tolerances, access roads, drainage, and the installation sequence. A building may need to be divided into transportable sections or shipped with some equipment installed later.
Site constraints also include flood level, seismic conditions, wind exposure, local setbacks, fire access, noise restrictions, and connection points. These factors can affect floor elevation, structural reinforcement, wall construction, door placement, and external equipment arrangement. I ask the buyer to provide a site plan and logistics information before confirming the prefabricated building size.
The sizing basis should state the design voltage, capacity, redundancy arrangement, equipment list, environmental conditions, growth phase, and applicable standards or authority requirements. It should also identify whether transformers, generators, batteries, and cooling equipment are inside the building or located externally. Without this definition, different suppliers may submit dimensions based on different assumptions and the quotations will not be directly comparable.
Indoor transformers and batteries can simplify weather protection but may increase the required building footprint, fire separation, ventilation, and structural design. Outdoor equipment can reduce internal area, yet it may require separate enclosures, weather protection, acoustic treatment, or longer cable connections. I compare the complete installed arrangement rather than judging size from the building alone.
At Pushen, I can support the project from equipment information review through layout coordination and prefabricated electrical building development. Our role is to convert the buyer’s electrical schedule, single-line diagram, site data, and environmental requirements into a coordinated manufacturing scope. The final design remains subject to the project engineer, equipment manufacturers, local authorities, and the agreed technical specification.
For a useful quotation, I recommend sending the available load schedule, equipment datasheets, preferred dimensions, voltage levels, redundancy target, cable-entry requirements, site location, transport limits, and expansion plan. I can then identify missing inputs, clarify assumptions, and separate confirmed requirements from preliminary planning values. This approach helps reduce redesign during manufacturing and installation.
To size a prefabricated electrical building for a data center, I first define capacity, list every item of equipment, create a scaled layout, add verified working and maintenance clearances, design cable routes, coordinate heat and safety requirements, reserve practical expansion capability, and validate transport and site constraints. The final length, width, and height should come from this coordinated model rather than from a standard building size. A smaller building is not automatically more efficient if it increases installation risk or prevents safe maintenance.
The next step is to prepare the equipment schedule and single-line diagram, mark the required operating modes and future phases, and share the site and logistics information with Pushen. With these inputs, we can develop a more reliable preliminary layout and identify the information needed for a final technical proposal. This gives the data center project a clear path from electrical capacity to a manufacturable prefabricated electrical building.
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