Thank you for the question. The standard for most providers of rack equipment is made by Rittal out of Germany. In fact, I believe that many of the major manufacturers OEM their racks from Rittal directly and place their logo and cable chases, mounting equipment and so on in the racks. I have had a good deal of luck using racks from APC's NetShelter line, but you should spec out what you need exactly and shop around. I would suggest specing out the mounting hardware required, cooling-air flow requirements, physical requirements (weight, security and so on) cabling and power. For 55 units you should be able to get some leverage from the vendors. I would talk with your purchasing department and get a purchasing agent involved so you can get off on the right foot (if you have a purchasing department, that is).
When buying the racks, make sure that you get the right mounting kits for your equipment and the right screws for the racks' mounting hardware. There is supposed to be a standard set of screws and mounting kits, but I have found this to be another fallacy of the industry with regards to standards. It is much better to get the right set of hardware up front versus having to use a Dremel to cut off a stripped screw (I've been there and don't ever want to go there again). Also, I would suggest staying away from any power tools to screw in the equipment in the racks as the power tools don't start these screws the right way and can often strip them before you even get started. Stick to manual tools to start the screws and then switch to a power tool that has an adjustable clutch to put the final turns on the screw.
I hope that I helped you out. Let me know.
This was first published in October 2005