Electrical Distribution System in a Data Center

There are many different loads in the data center, such as IT devices, air conditioners (CRAC Units), pumps, lighting, etc. The critical supply from the utility / transformer / generator to the load is enabled by various types of power equipment. We are going to illustrate these equipment that are critical and without which it would not be possible to operate the data center.

Figure 1 is a block diagram of an electrical distribution system showing the name and the typical location of the electrical distribution equipment in a data center and the power flow path (Uptime Institute Tier Level II, N+1 Design) . This diagram is only an example of an electrical architecture and attempts to include all the possible major types of equipment used and their typical location in a data center. In the real world, a typical data center electrical design has much more complexity and diversity than that in this diagram.

Uptime Institute Tier II, N+1 Design

Figure 1 

Uptime Institute Tier III Design

Uptime Institute Tier IV, 2N+1 Design

Tracing the flow of power along its path (starting from the utility to the IT load) in the figure 1 above. It shows 8 essential facilities are critical for the power supply. This facilities distribute power to the downstream loads and also protect the power distribution system in the data center:

• Medium-voltage switchgear
• MV/LV transformer
• Low-voltage switchgear / switchboard / automatic transfer switch (ATS)
• UPS system with input/output switchboard and UPS distribution switchboard
• Power distribution Units (PDUs) and remote power panels (RPPs)
• Busway
• Panelboard
• Rack PDUs (rPDUs) / outlet strips

All facilities above, except for rack PDUs (rPDUs), are considered to be assemblies containing circuit breakers, switches, various types of relays, buses and connections, and control and auxiliary devices. Each device is optimized for long life and ease of maintenance.

The IEC 61947 & IEC 62271, which specifies the HV and LV switchgear terminology, considers switchboard to be the same as switchgear. For some regions like, North American, switchgear and switchboard are specified differently by ANSI and UL standards.

About Us


SMA combines with professional Chartered Engineers (CEng) from the Institute of Engineering Technology (IET), the Chartered Institute of Building Services Engineers (CIBSE) and the Hong Kong Institution of Engineers (HKIE). Our engineers have more than 20 years experience in data center design & build, building services engineering and energy conservation in the private and public sectors.

The team prepares the engineers and IT personnel to face any challenges in data centers and critical facilities of any size, in any location. For other design considerations / topics in data center and critical infrastructure, please visit 


(1) Site Selection,
(2) Space Planning,
(3) Cooling,
(4) Redundancy,
(5) Fire Suppression,
(6) Meet Me Rooms,
(7) UPS Selection,
(8) Raised Floor,
(9) Code & Standards,
(10) Transformers and Harmonic Distortion,
(11) Multi-mode UPS Systems,
(12) Electrical Rooms,
(13) Generator Systems,
(14) Generator Fuel Systems,
(15) Battery Systems,
(16) Earthing / Grounding and Bonding, etc.