The Raritan Blog

Rack PDUs Outlet Density and Types

Jessica Ciesla
November 14, 2019

As the need for power consumption per server has changed, so too have the outlet density and types of rack PDUs. In fact, in order to support the power-hungry IT equipment that seems to dominate data centers, rack PDUs have become increasingly more powerful. Today's data centers see densely packed racks, greater watts per square foot, and higher than every power consumption. Understanding rack PDUs outlet density and types is a vital to keeping data centers running properly, without overloading servers or creating costly outages.

Rack PDUs Outlet Density And Types 101

Every rack PDU has a certain number of outlets that it can support. The number of outlets supported will vary based on the physical size (i.e. the length, width, and depth) of the PDU, as well as the total space available and the power handling capacity of the PDU. In layman's terms, in order to calculate the number of outlets that a PDU will support you need to look at the following three components:

• Physical size;
• Total space available for mounting both outlets and internal components; 
• The power handling capacity;

Putting these three components together, you might discover that a 1U rack-mount PDU could have enough space to handle eight 120V/15A NEMA 5-15R outlets. Conversely, a 2U rack-mount PDU, which is larger, has more available space, and can handle greater power consumption levels might be able to support twenty 120V/15A NEMA 5-15R outlets.

With the above factors in mind, data center managers must carefully assess the power needs and configuration of their blade servers and connected devices. As a rule of thumb, many devices that require a moderate amount of power, will need to be supported by a large amount of moderate power outlets. The latter scenario would require two rack PDUs that are only loaded to 40 percent to create a redundant power source, so that if one power feed fails, the other feed will not reach higher than 80 percent. This strategy ensures continuity in the event of one power failure; however, it is only practical for moderate power demands. If there is a high-power consumption, then a different configuration is advisable.

In the case of high-power consumption devices, such as blade servers, storage, or network devices, the total amount of required power as well as the number and type of outlets will vary. To calculate the outlet density and types of rack PDUs needed, data center managers will have to look at the following factors:

• The number of devices demanding high levels of power;
• The density for each device; 
• How the power supplies are configured and the number of devices that will be deployed for each rack;

With the above factors in mind, if a few devices that require a substantial amount of power are being used, then outlets that deliver high power loads will be required. These outlets might include IEC C-13 (up to 250V, 16A), C-19 (up to 250V, 32A), NEMA L6-20R (up to 250V, 20A, 16A rated), or L6-30R (up to 250V, 30A, 24A rated).

Choose The Right Rack PDUs Outlet Density And Types With The Help Of The Raritan Team

No matter the size of the data center, choosing the right rack PDUs outlet density and type is imperative to ensuring that systems aren't overloaded, power demands are met, and uptime is maintained. 

Whether you have a lot of devices requiring moderate power, or a few devices that need a high level of power, the Raritan team is here to help. 

To discover the right rack PDUs for your data center needs, contact a Raritan team member today.