Figure 40: Connecting The Power Supply Cables To An Ex4500 Switch - Juniper EX4500 Hardware Manual

EX4500 Switch Hardware Guide
146
Ensure that the power source circuit breaker is open so that the voltage across the
4.
DC power source cable leads is 0 V and that the cable leads do not become active
while you are connecting DC power.
Verify that the DC power cables are correctly labeled before making connections to
5.
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 and DC cables to chassis ground:
–48V RTN
The cable with very high resistance (indicating an open circuit) to chassis ground
is negative (–) and will be installed on the
The cable with very low resistance (indicating a closed circuit) to chassis ground is
positive (+) and will be installed on the
CAUTION: You must ensure that power connections maintain the proper
polarity. The power source cables might be labeled
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.
Install each power cable lug on the DC power input terminal, securing it with the locking
6.
screw, (see Figure 40 on page
of torque to tighten each locking screw.

Figure 40: Connecting the Power Supply Cables to an EX4500 Switch

Slide the plastic cover over the input terminal block. See
7.
–48V (input) DC power input terminal.
(return) DC power input terminal.
RTN
146). Apply between 9 in.-lb (1.1 Nm) and 12 in.-lb (1.3 Nm)
Copyright © 2017, Juniper Networks, Inc.
and to indicate
(+) (–)
Figure 41 on page 147 .