The quick rule is to place heavier equipment lower on the rack. This not only helps keep the rack more stable but it also makes for easier access to heavy servers when troubleshooting.
Starting at the bottom of the rack would be the UPS and tower type servers and above that would be multiple RMU rack mount equipment like servers and switches. If any of the large equipment is on sliding rails or sliding shelves, then the Wall to Rack Kit should considered.
Next, is a good place for a locking drawer to store back-up tapes, patch cords and test equipment. The next area is about mid-height in a 7' rack. This is a logical place to locate a keyboard and shelf for comfortable use. Just above that would go a monitor shelf.
Further up would go small switches, patch panels and horizontal wire managers. The horizontal managers are typically placed above, below, and between patch panels. Up near the top, is a good location for single sided shelves to support small equipment like tape drives, modems, and KVM switchboxes.
If you are not sure which shelf would be best for your equipment, you can see our shelves in more detail in our eCatalog or contact Technical Support.