2-4 Chapter 2Installing Single and Multiple Cabinet Configurations4. Place the upper cabinet on top of the centre cabinet ensuring that the upper cabinet locating bumpsare snug in the centre cabinet locating dimples. Install two of the provided screws in the dimples inthe lower panel of the upper cabinet and the other two provided screws in the dimples in the rearlower panel of the upper cabinet.5. Replace the rear panel of the upper cabinet.6. Proceed with the installation of the power supply unit(s), grounding, power connections, controlcards, interface cards and optional equipment as described in the following chapters.Rack Mounting CabinetsPrepare all of the cabinets by removing the side and front covers of the cabinets prior to installation toavoid damaging the covers and to allow access to the interior. In addition, the top covers and the bot-tom panels from the cabinets must be removed.1. Remove the four screws holding each side cover support bracket and remove the brackets fromboth sides of the cabinet (Figure 2-3). These brackets are not required for rack mounting.2. Remove the ground bar from the left side of the cabinet.3. Remove the breakout panels from the base of all the cabinets to allow cable access.4. Install the cabinets in the rack and secure each cabinet with eight screws in the mounting flangeholes (Figure 2-4). (If mounting in a ‘600 wide’ rack, leave a space of roughly 5 cm between cabi-nets to allow cable access, and use the longer HDLC cables.)5. Reattach the ground bar to each cabinet.6. Proceed with the installation of the power supply unit(s), grounding, power connections, controlcards, interface cards and optional equipment as described in the following chapters.Adding Expansion Cabinet(s) to a WorkingSystemIf you already have a working OfficeServ500 ‘L’ version single- or two-cabinet system, you can up-grade it with the addition of one or more expansion cabinets at a later time. The procedure to adopt forsuch an upgrade will be one of those discussed above, depending on whether you are adding one ortwo expansion cabinets. Before beginning the installation, switch off all system power andremove all cables from the working system.If upgrading from a single cabinet system to a two cabinet system, see Two Cabinet Installation. If up-grading from a single cabinet system or a two cabinet system to a three cabinet system, see ThreeCabinet Installation. If you are rack mounting the new cabinet(s), see Rack Mounting Cabinets, above.Once installed, you can add the power supply, power connections and interface cards to the new cabi-net(s) as described in the following chapters.