Installing a DC Power Supply

Each power supply in a DC-powered router must be connected to earth ground. A ground terminal is provided on each DC power supply for this purpose.

To install a DC power supply (see Figure 94):

1. Ensure that the voltage across the DC power source cable leads is 0 V and that the cable leads cannot become active during installation.

   Caution: You must ensure that power connections maintain the proper polarity. The power source cables might be labeled (+) and (–) to indicate their polarity. There is no standard color coding for DC power cables. The color coding used by the external DC power source at your site determines the color coding for the leads on the power cables that attach to the terminal studs on each power supply.

2. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist and connect the strap to the ESD point on the chassis, or to an outside ESD point if the router is disconnected from earth ground. For more information about ESD, see Preventing Electrostatic Discharge Damage.
3. Using both hands, slide the power supply into the chassis until you feel resistance.
4. Firmly push the power supply into the chassis until it comes to a stop. Make sure that the power supply faceplate is flush with any adjacent power supply faceplate.
5. Use a Phillips screwdriver to remove the clear plastic cover protecting the terminal block.
6. Within the terminal block, remove the two center screws next to the labels –48 VDC and RTN.

   Each screw contains a captive washer to secure a power cable lug to the terminal block.

7. Using one of the removed screws, secure the positive (+) DC source power cable lug to the RTN terminal. Tighten the screw until snug. Do not overtighten. Apply between 8 lb-in. (0.9 Nm) and 9 lb-in. (1.02 Nm) of torque to the screw.
8. Using the other removed screw, secure the negative (–) DC source power cable lug to the –48 VDC terminal. Tighten the screw until snug. Do not overtighten. Apply between 8 lb-in. (0.9 Nm) and 9 lb-in. (1.02 Nm) of torque to the screw.

   Note: Each power supply must be connected to a dedicated DC power feed. For information about connecting to DC power sources, see Connecting Power.

9. Dress the power cables appropriately.
10. Replace the clear plastic cover over the terminal block.
11. Verify that the power cord does not block access to router components or drape where people might trip on it.
12. Press and release the power button to power on the router. Verify that the POWER LED lights steadily.