4 Installing a Fan-Speed Controller in Cisco 3620 Routers
Never assume that power is disconnected from a circuit. Always check.
Do not work alone if potentially hazardous conditions exist.
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• Look carefully for possible hazards in your work area, such as moist floors, ungrounded power extension cables, and missing safety grounds.
Before working on the router, turn OFF the power and unplug the power cord. Disconnect all power before doing the following:
— Installing or removing a router chassis
— Working near power supplies
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Warning Do not touch the power supply when the power cord is connected. For systems with a power switch, line voltages are present within the power supply even when the power switch is OFF and the power cord is connected. For systems without a power switch, line voltages are present within the power supply when the power cord is connected.
Follow these guidelines when working on equipment powered by electricity:
• Locate the emergency power-off switch in the room in which you are working. Then, if an electrical accident occurs, you can quickly shut the power OFF.
Warning Ultimate disposal of this product should be handled according to all national laws and regulations.
Safety with Electricity
Warning Before working on equipment that is connected to power lines, remove jewelry (including rings, necklaces, and watches). Metal objects will heat up when connected to power and ground and can cause serious burns or weld the metal object to the terminals.
Warning To avoid electric shock, do not connect safety extra-low voltage (SELV) circuits to telephone-network voltage (TNV) circuits. LAN ports contain SELV circuits, and WAN ports contain TNV circuits. Both LAN and WAN ports may use RJ-45 connectors. Use caution when connecting cables.
Warning Hazardous network voltages are present in WAN ports regardless of whether power to the router is OFF or ON. To avoid electric shock, use caution when working near WAN ports. When detaching cables, detach the end away from the router first.
Warning Before opening the chassis, disconnect the telephone-network cables to avoid contact with telephone-network voltages.
Warning Do not work on the system or connect or disconnect cables during periods of lightning activity.
