What height should my network or server cabinet be?
The interior height, which is important for usability, is measured in U (height unit) in an internationally standardized way. 1 U is 44.45 mm. The OUTSIDE height of the cabinet is then defined by the roof and floor construction of the respective cabinet type.
Some standard dimensions have become established: cabinets with an external height of 1200 mm usually have a useful height inside of 24 or 25 U. At 2000 mm external height, the usable internal height varies between 41 and 43 U depending on the manufacturer.
You calculate the cabinet height and useful height you need by:
- First, convert the height of all fixtures whose height is not specified in height units (U) into height units. These include stand-alone UPS, desktop computers, etc.
- Add the value obtained to the U value of the other fixtures. Theoretically, the useful height of your cabinet would now be determined, but in practice it has proven useful to add some “buffers”. So you should
- Allow about 1-2 U of free space between servers and internals, which generate a relatively large amount of waste heat, so that they do not heat each other up.
- Even if you want to install fans (units) in the floor or roof, you should leave 2-3 U of free space there to achieve good airflow and thus optimal air circulation.
- Now you have a reference value for the useful height in U. An important final consideration should be future-proofing. Is it foreseeable that in the future other internals will take a place in your network or server cabinet? Then it would make sense to buy a cabinet with a little more useful height, so as not to have to replace the cabinet a short time later. This saves work and money.
In short:
Height of all fixtures
+ free space between servers
+ free space for fans
+ future proof
= useful height
