nimum of two people when lifting heavy switches. Of- ten, a third person can guide the chassis into the rack. The chassis should be moved only after all the modules and power supplies have been removed. Power Each module will draw a certain amount of power (measured in watts). When you've determined which modules will be present in your switch, you must add up the power requirements for all of them. The result will determine what size power supplies you should order. For redundancy, each power supply in the pair should be able to provide all the power necessary to run the entire switch, including all modules. So, if your modules require 3,200 watts in total, you'll need two 4,000-watt power supplies for redundant power. You can use two 3,000-watt power supplies instead, but they will both be needed to power all the modules. Should one power supply fail, some modules will be shut down to conserve power. Chapter 2: Hubs and Switches Depending on where you install your switch, you may need power supplies capable of using either AC or DC power. In the case of DC power supplies, make sure you specify A and B feeds. For example, if you need 40 amps of DC power, you'd request 40 amps DC-A and B feeds. This means that you'll get two 40-amp power circuits for failover purposes. Check the Cisco documentation regarding grounding information. Most collocation facilities supply positive ground DC power. For AC power supplies, you'll need to specify the voltage, amperage, and socket needed for each feed. Each power supply typically requires a single feed, but some will take two or more. You'll need to know the electrical terminology regarding plugs and re- ceptacles. All of this information will be included in the documentation for the power supply, which is available on Cisco's website. For example, the power cord for a power supply may come with a NEMA L6-20P plug, which will require NEMA L6-20R re- ceptacles. The P and R on the ends of the part numbers describe whether the part is a plug or a receptacle (the NEMA L6-20 is a