Cabinet Load Ratings—Why They Matter & Why They’re Changing
Optimizing floor space and decreasing data center operating costs requires more active gear inside cabinets and enclosures. As a result, cabinet designs are wider, deeper and taller. Only a few years ago, most enclosures offered 42 or 45 RUs of space. Today, however, many cabinets offer 48 RUs of space with some offering as much as 52 RUs, or more.
As cabinets grow in size to accommodate more active gear, they also get heavier. Cabinets that are too heavy can be difficult to move and result in load capacity issues. It’s becoming crucial to analyze load ratings (also known as “load capacities”) when selecting enclosures.
Consider the following—
- Static load rating: How much weight a cabinet can hold when racks are loaded in the data center
- Dynamic load rating: How much weight a cabinet can accommodate when shipped fully loaded—an important consideration with data-center-ready services increasing in popularity
- Rolling load rating: How much weight a cabinet can tolerate when moved/rolled across the floor
Most enclosures are listed against UL 2416 for static load. Just a few years ago, the average static load rating was ~1500 pounds. Today, static load ratings of 3000 pounds aren't unusual and in many cases, dynamic and rolling cabinet load ratings will be the same.
It’s also important to note that static, dynamic and rolling load ratings are not the same as a cabinet seismic rating. Seismic ratings indicate how much protection rack-mount equipment will receive during an earthquake. While a cabinet’s width, depth and height can influence load ratings, there are other factors to consider.
Cabinet Construction
There are two main enclosure types: fully welded enclosures and enclosures with bolted-together components. A bolted design accommodates flat shipping and saves on shipment costs, has higher load ratings and can adequately support more weight from active gear. Corner post geometry and the steel gauge (thickness) used to construct corner posts and mounting rails can also influence a cabinet’s load rating.
Regular vs High-Capacity Casters
Before shipping, cabinets are often loaded with switches, servers and other necessary components. Cabinets are then tested and commissioned. Once testing is complete, cabinets are rolled into trucks and shipped.
Moving an enclosure across the floor not only requires an adequate rolling load rating—it also requires correct casters. Heavy-duty casters make a significant difference in accommodating a heavier rolling load rating and withstanding rolling movement. There’s a notable load-rating difference (up to 1000 pounds or more) between a cabinet with regular-capacity casters and a cabinet with high-capacity casters.
Built-In Levelers
Levelers don’t impact a cabinet’s static, rolling or dynamic load rating however, they can make it easier to safely move a cabinet. For best performance of active gear, enclosures must be level. Built-in levelers underneath enclosures allow installers to move and level cabinets once in place. A few years ago, cabinets were leveled before equipment was placed inside, making it difficult to move the cabinet and ensure everything remained level. Today however, built-in levelers enable advance equipment installation and level the enclosures once cabinets are loaded.
Vibration
Vibration isn't a direct influencer on load ratings, either however, it's important the cabinet be able to withstand vibration and shocks when being moved, without distortion. Oftentimes, special shock-absorbent pallets are used to insulate active gears mounted in the enclosure to offer additional protection during transport.
Belden
Belden’s X-Series (XHM & XHS) Enclosures guarantee a static load rating of 3000 pounds and are designed to seamlessly integrate power distribution, airflow containment/management, networking connectivity and cable management. These enclosures are shipped fully assembled and configured to exact specifications (e.g., several options for doors, side panels, passive chimneys or active AEHC units and PDU mounting).
Learn more about Belden data center solutions to help maximize space, speed up deployment, reduce downtime and save on time and cost.
About the Author
Denis is a product line manager for Belden R&E folio. Denis holds a BSc in Mech Eng (1989), His focus at Belden is helping data center managers find solutions to density challenges (cable mng, heat, power). He has been involved with the deployment of over 3 million square feet of white space. In his spare time, Denis enjoy golfing and MTB.