Juniper EX4300 Hardware Manual page 211

Copyright © 2017, Juniper Networks, Inc.
To meet safety and electromagnetic interference (EMI) requirements and
to ensure proper operation, you must connect the chassis to earth ground
before you connect it to power. For installations that require a separate
grounding conductor to the chassis, use the protective earthing terminal
on the switch chassis to connect to the earth ground. For instructions on
connecting earth ground, see
Switch" on page
Install the power supply in the chassis. For instructions on installing a DC power supply
in an EX4300 switch, see
page 236.
Ensure that you have the following parts and tools available:
DC power source cables (14–16 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 51 on page 192
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.
Chapter 12: Connecting the Switch to Power
"Connecting Earth Ground to an EX Series
179.
"Installing a DC Power Supply in an EX4300 Switch" on
shows how to secure ring lugs to the terminals on the
189