Cisco Gigabit Switch Router 12008 Installation And Configuration Manual page 299

To install a second (redundant) DC-input power supply, you must first satisfy the following
requirements:
•
Ensure that a dedicated 40A service is available for the second power supply.
•
Ensure that the power cables from the source DC service circuit breaker to the DC-input
power supply are made of 4 AWG, high-strand-count copper wire.
•
Ensure that the lugs on the source DC power cables (see Figure 7-5) have dual-holes,
centered 0.625 inch apart, and that they will fit over the 0.25-inch M6 (metric) threaded
terminals on the DC power supply faceplate (see Figure 7-6).
Caution AC-input and DC-input power supplies cannot be used together in the same
router. Such a configuration is not supported and may damage the system.
Note If you are adding a second (redundant) DC-input power supply to your router, you
will need to obtain the proper source DC power cables and terminal lugs from a commercial
supplier in order to connect source DC power to the new DC-input power supply. These
parts are not available from Cisco Systems.
Adding, Removing, or Replacing a DC-Input Power Supply
Maintaining the Cisco 12008 7-19