Power Distribution Units for Data Centers

A PDU (Power Distribution Unit) controls and distributes power to computers, servers and networking devices within an IT environment. Almost every equipment rack used to store compute, storage or network equipment requires a rack mounted PDU to distribute power. But, if you’re new to the industry or are unfamiliar with electrical power distribution systems, selecting a PDU can be challenging. Check out our earlier blog - PDU 101 - for an introduction into Power Distribution Units. 

While each IT infrastructure is different, here are some key questions you must answer to select the right PDU for your environment.

  • Where will I install my PDU?
  • What type of power supply will I need?
  • How much power does my equipment need?
  • What kind of input plugs are required?
  • How many outlets will be needed?
  • What kind of functionality do I want?

Answer the first five questions before thinking about what features and functionality will help maximize your facility.

Where will I Install my PDU?

Power distribution equipment can be used throughout a data center or IT environment – in rows, racks, rooms, and even modularly. But when selecting a rack PDU, the first thing to consider is the form factor. You’ve got two configuration options when deciding on a rack PDU: vertical and horizontal.

Vertical PDUs

A vertical PDU’s form factor can be tailored to fit most rack heights. They’re installed at the back or side of the rack enclosure, so they don’t take up critical equipment-mounting space inside the rack. Use a vertical PDU in a full-height , free-standing rack to maximize possible equipment connections.

Horizonal PDUs

Horizontally mounted PDUs are installed within the rack U space and sit horizontally in line with your IT equipment. Typically, horizontal units take up 1U or 2U of rack space and have 8-16 outlets. Horizonal PDUs should be used in smaller wall-mount racks.

What Type of Power Supply Will I Need?

A three-phase circuit delivers more power than a single-phase circuit. Where they’re used depends on your location and building type. Single-phase power is common in small offices. Three-phase power is used in data centers, large critical facilities and commercial environments.

How Much Power Does My Equipment Need?

Each piece of equipment should list the maximum amount of power it can consume either in volt-amperes (VA) or in watts (W). After adding up the total power consumption of all your rack mounted equipment, that total should be lower than what your power source is rated for. In the US, the voltage used to power servers and networking equipment is typically 120V or 208/240V. Europe and Asia typically provide 230V power.

What kind of Input Plugs do I need?

The input plug must match the branch circuit receptacle (outlet) at the rack. For safety, plugs and matching receptacles (outlets) are physically different for each type of branch circuit connection to prevent accidental connection between incompatible devices.

Which input plugs are used most frequently depends on where your data center’s location. The American National Standards Institute (ANSI)/National Electrical Manufacturers Association (NEMA) standard is used primarily in North America. The International Electrotechnical Commission (IEC) is used globally, including for some high Amperage connections in North America.

How Many Outlets do I Need?

A good rule of thumb is to make sure there are at least enough PDU outlets for the number of input plugs you need to connect. You should also consider having extra outlets for future growth.

Features & Functionality

Look for part three of our PDU blog series soon where we'll help you answer our last question. We'll share the functionality of various rack PDUs and which features are best for different IT environments. If you'd like help selecting the right PDU for your planned or existing infrastructure, CONTACT US today to get the conversation started.