Cisco Gigabit Switch Router 12008 Installation And Configuration Manual page 288

Adding, Removing, or Replacing an AC-Input Power Supply
Note
source of power with a 20A service. It is also recommended that you use an uninterruptable
power source (UPS) for your site to protect against a site power failure.
To add a second (redundant) AC-input power supply to the router, perform the following
steps:
Step 1
Step 2
Step 3
Step 4
Warning
to install the unit in the power supply bay.
Step 5
Step 6
7-8
Cisco 12008 Gigabit Switch Router Installation and Configuration Guide
It is recommended that you connect each AC-input power supply to an independent
Locate the source AC circuit breaker that will service the AC-input power
supply; ensure that this circuit breaker is set to the OFF position.
For added safety, tape the circuit breaker handle in the OFF position.
Using a 1/4-inch flat-blade screwdriver, loosen the captive installation screw on
the blank filler panel covering the vacant (upper) power supply bay; remove the
filler panel and retain it for possible future use.
Presumably, you will install the new power supply in the upper power supply
bay, since, by convention, a single AC-input power supply is installed in the
lower bay.
Ensure that the rotary power switch on the faceplate of the new power supply
that you intend to install is set to the standby (OFF) position (see Figure 7-3).
Grasp the carrying handle on the new power supply with one hand; while lifting
the power supply, place your free hand beneath the unit to support its weight.
The AC-input power supply weighs 17 lb (7.73 kg). For safety, use both hands
Position the power supply appropriately for insertion into the vacant upper bay.
Gently slide the unit into the bay, carefully seating it so that the power supply
faceplate rests flush against the sheet metal of the power supply bay.