Juniper EX4300 Hardware Manual page 199

Copyright © 2015, Juniper Networks, Inc.
Ensure that you have the following parts and tools available:
DC power source cables (12–14 AWG) with ring lug (Molex 190700067 or equivalent)
(not provided)
Phillips (+) screwdriver, number 2 (not provided)
Multimeter (not provided)
A 14 AWG (2 mm²), minimum 90°C wire grounding cable, or one permitted by the local
code, with a Panduit LCC10-14BWL or equivalent grounding lug attached (not provided)
Two 10-32 x .25 in. screws with #10 split-lock washer (not provided)
Two #10 flat washers (not provided)
To connect DC power to an EX4300 switch:
Attach the grounding strap to your bare wrist and to a site ESD point.
1.
NOTE: The power supply slots are at the right end of the rear panel on
24-port and 48-port switches, and at the left end on 32-port switches.
Figure 52 on page 179
the DC power supply installed on 24-port or 48-port EX4300 switches.
The procedure is the same for 32-port EX4300 switches.
Verify that the DC power cables are correctly labeled before making connections to
2.
the power supply. In a typical power distribution scheme where the return is connected
to chassis ground at the battery plant, you can use a multimeter to verify the resistance
of the –48V and RTN DC cables to chassis ground:
The cable with very low resistance (indicating a closed circuit) to chassis ground is
positive (+) and will be installed on the V+ (return) DC power input terminal.
The cable with very high resistance (indicating an open circuit) to chassis ground
is negative (–) and will be installed on the V– (input) DC power input terminal.
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 DC
power input terminals on each power supply.
Ensure that the input circuit breaker is open so that the voltage across the DC power
3.
source cable leads is 0 V and that the cable leads will not become active while you
are connecting DC power.
Chapter 12: Connecting the Switch to Power
shows how to secure ring lugs to the terminals on
177