Disconnecting DC Power from the Router

To disconnect DC power from the router, follow this procedure (see Figure 74):

1. On the console or other management device connected to the master Routing Engine, enter CLI operational mode and issue the following command to shut down the router software. (If two Routing Engines are installed, also issue the command on the backup Routing Engine.)
   user@host> request system halt

   Note: Wait until a message appears on the console confirming that the operating system has halted.

   For more information about the command, see the JUNOS System Basics and Services Command Reference.

2. For each power supply, press the power switch on the power supply faceplate to the OFF (O) position.

   Note: If you are power cycling the power supply rather than shutting it off for a time, wait at least 60 seconds after turning it off before turning it back on. If you need to power it off again, wait for at least 60 seconds after powering it on.

3. Shut off the power flowing from both external power sources, so that the voltage across the leads of the power cables is 0 V. Ensure that there is no chance that the cable leads might become active during the procedure.
4. Using a Phillips screwdriver, loosen and remove the screws securing the protective shield over the terminal studs on the power supply faceplate. Remove the cover.
5. Using a 7/16-in. nut driver or wrench, loosen the outer nut securing the cable lug to each terminal stud. Remove the outer nuts and washers, leaving the inner nut and washer on each stud.

   Caution: Do not substitute a metric nut driver or wrench. A tool that does not fit the nuts exactly can damage them.

6. Slide the cable lug off of each terminal stud. Leave the inner washer and nut on each stud.
7. If you are decommissioning the router, loosen and remove the nuts and washers that secure the grounding lug to the chassis and remove the grounding lug.
8. If not immediately attaching replacement cables, replace the protective shield on each power supply and tighten the screws that secure it to the supply.
9. Verify that the removed cables are not touching or blocking access to any router components.

Figure 74: Disconnecting DC Power Cables