Installing the Circuit Breaker Box

To install the circuit breaker box, follow this procedure (see Figure 100):

1. Verify that there is no power flowing from either external power source, 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.
2. For each power supply, verify that the power switch on the circuit breaker box is in the OFF (O) position.
3. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist and connect the strap to one of the ESD points on the chassis. Make sure the router is attached to a proper earth ground. For more information about ESD, see Preventing Electrostatic Discharge Damage.
4. Align the guide pin on the back of the circuit breaker box with the opening in the chassis, then push the circuit breaker box straight in.
5. Tighten the thumbscrews at the top and bottom edge of the circuit breaker box. Using a Phillips screwdriver, tighten the screw at each corner of the box.
6. Slide the power cable lugs for both power sources onto the terminal studs on the circuit breaker box:
   • Connect the positive (+) source cable lugs to the return terminals on the circuit breaker box, which are labeled RTN(+).
   • Connect the negative (–) source cable lugs to the input terminals on the circuit breaker box, which are labeled –48V.
7. Slide a washer and then screw a nut onto each terminal stud (if the washers and nuts were not installed on the studs, they should be in the accessory box). Using a 7/16-in. nut driver or wrench, tighten the nuts.

   Do not substitute a metric nut driver or wrench. A tool that does not fit the nuts exactly can damage them. If a 7/16-in. tool is not available, use pliers or an adjustable wrench.

8. Replace the protective shield on the circuit breaker box and tighten the screws that secure it to the box.
9. Replace the rear lower impeller assembly by lining up the rails with the guides inside the chassis, pushing the impeller straight in, and tightening the thumbscrew at each corner of the impeller cover. For complete instructions, see Installing the Rear Lower Impeller Assembly.
10. Apply voltage from the DC power sources to the power cables so the router receives power.
11. Press the switches on the circuit breaker box to the ON ( | ) position.
12. Confirm that the LEDs on the power supply faceplates indicate correct operation: the green CB ON LED lights steadily, the blue OUTPUT OK LED blinks briefly, then lights steadily, and the amber CB OFF LED does not light.

    After powering off a power supply, wait at least 60 seconds before turning it back on. After powering on a power supply, wait at least 60 seconds before turning it off. If the router is completely powered down when you power on the power supply, the Routing Engine boots as the power supply completes its startup sequence. If the Routing Engine finishes booting and you need to power down the router again, first issue the CLI request system halt command. For more information, see Disconnecting Power from the Router. After a power supply is powered on, it can take up to 60 seconds for status indicators—such as LEDs on the power supply, show chassis commands, and messages on the craft interface LCD—to indicate that the power supply is functioning normally. Ignore error indicators that appear during the first 60 seconds.