Corporate networks are complex systems of PCs, servers, printers, and the devices that connect them. Getting everything to work in harmony requires bundles of cables, and managing all those cables from inside a telecommunications closet can be a daunting task. To connect cable bundles to rackmounted equipment (like patch panels, hubs, switches, or routers), you need to direct the bundles overhead, vertically, and horizontally.

A popular choice for overhead cable routing is a ladder rack. Ladder racks come in many varieties. They can run along a wall supported by brackets or they can be installed overhead and supported by a threaded rod. Ladder racks can support large cable bundles neatly and safely. Because bundles lie flat on a ladder rack, cables aren’t subjected to harsh bends. You can run ladder racks directly to the top of most standard telecommunications racks that conform to TIA/EIA standards.

Use vertical cable managers to route cable bundles along the sides of a rack. These “cable troughs” as they’re sometimes called can be single sided—or double sided to route cable bundles to the rear of equipment and to the ports on the front as well. Vertical cable managers usually come with some type of protection for the cable, such as grommeted holes to protect the cable jacket or a cover that may clip on or act as a door.

Horizontal cable managers are usually a series of rings that directs cables in an orderly fashion toward the ports of hubs, switches, and patch panels.

The National Electrical Manufacturers’ Association (NEMA) issues guidelines and ratings for an enclosure’s level of protection against contaminants that might come in contact with its enclosed equipment.

There are many numerical NEMA designations; we’ll discuss NEMA enclosures relevant to our on-line catalog: NEMA 3, NEMA 3R, NEMA 4, NEMA 4X, and NEMA 12.

NEMA 3 enclosures, designed for both indoor and outdoor use, provide protection against falling dirt, windblown dust, rain, sleet, and snow, as well as ice formation.

The NEMA 3R rating is identical to NEMA 3 except that it doesn’t specify protection against windblown dust.

NEMA 4 and 4X enclosures, also designed for indoor and outdoor use, protect against windblown dust and rain, splashing and hose-directed water, and ice formation. NEMA 4X goes further than NEMA 4, specifying that the enclosure will also protect against corrosion caused by the elements.

NEMA 12 enclosures are constructed for indoor use only and are designed to provide protection against falling dirt, circulating dust, lint, fibers, and dripping or splashing noncorrosive liquids. Protection against oil and coolant seepage is also a prerequisite for NEMA 12 designation.

Understanding cabinet and rack measurements.
The main component of a cabinet is a set of vertical rails with mounting holes to which you attach your equipment or shelves. When you consider the width or height of a cabinet, clarify whether the dimensions are inside or outside.

The first measurement you need to know is the width of the rails. The most common size is 19 inches with hole-to-hole centers measuring 18.3 inches. There are also 23-inch and 24-inch cabinets and racks. Most rackmount equipment is made to fit 19-inch rails but can be adapted for wider rails.

After width, the most important specification is the number of rack units, abbreviated as “U.” It’s a measurement of space available to mount equipment. Because cabinet width is standard, the amount of space is what determines how much equipment you can actually install. Remember, this is an internal measurement of usable space and is smaller than an external measure of the cabinet or rack.

One rack unit (1U) is 1.75 inches of usable space and is usually, but not always, measured vertically. So, for example, a rackmount device that’s 2U high takes up 3.5 inches of rack space. A rack that’s 20U high has 35 inches of usable space.

Choosing the right cabinet.
Here’s a quick checklist of features to keep in mind before you choose a cabinet for servers or other network devices:
• High-volume airflow.
• Adjustable rails.
• Rails with M6 square holes.
• Moisture and dust resistance.
• Air filters.
• Front and/or rear accessibility.
• Locking doors.
• Left- or right-hinging doors.
• Power strips and cable organizers.
• Interior lighting.
• Preassembly.
• Availability of optional shelves, fans, and casters.
• Cable management rails, space, and knockouts.
• Extra depth to accommodate newer, deeper servers.

Don’t forget to accessorize.
Even if your cabinet is in a climate-controlled room, you may need to add a fan panel to help keep your equipment from overheating. It’s especially important to have ventilation in an enclosed cabinet.

Rackmount power strips mount either vertically or horizontally. Some have widely spaced outlets to accommodate transformer blocks. Some power strips include surge protection.

Mission-critical equipment should be connected to an uninterruptible power supply (UPS). A UPS keeps your equipment from crashing during a brief blackout or brownout and provides you with enough time to shut down everything properly in a more extended power outage.

For accessories that make cabling easier, just take a look at our many cable management products. We have cable management guides, rackmount raceways, horizontal and vertical organizers, cable managers, cable hangers, and much more.