Overview of the Cisco 12008
Cisco 12008 Gigabit Switch Router Installation and Configuration Guide
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The three contacts on the alarm terminal block are labeled as follows:
•COM (Common)—This contact is common to both the Normally Open (NO) and the
Normally Closed (NC) contacts.
•NO (Normally Open)—These contacts on the alarm terminal block are open as long as
no overcurrent condition is detected in the power supply. When the power supply circuit
breaker is tripped during an overcurrent condition, these contacts are closed.
•NC (Normally Closed)—These contacts on the alarm terminal block are closed as long
as no overcurrent condition is detected in the power supply. When the power supply
circuit breaker is tripped during an overcurrent condition, these contacts are open.
Table1-1 summarizes the status of the contacts on the alarm terminal block during an
overcurrent condition in the power supply.
Table1-1 Circuit Breaker Status Indicated by the Ala rm Terminal Block
If you decide to use an external alarm-monitoring facility in conjunction with the alarm
terminal block, note that the contacts on the alarm terminal block have a rating of 60 VDC
at 1A maximum.

Source DC Input Connectors

The faceplate of the DC-input power supply incorporates three sets of terminals for
connecting source DC power to the power supply (see Figure1-7). From top to bottom,
these terminals are identified as follows:
•Ground
•+ (positive)
•– (negative)
Circuit Breaker Position NC Contact NO Contact
OFF (tripped) Open Closed
ON Closed Open