Juniper Networks EX4200 - Manual (Page 175)

■ Phillips (+) screwdriver, number 2
Before you begin connecting DC power to an EX3200 or EX4200 switch:
■ Ensure that you have taken the necessary precautions to prevent ESD damage
(see “Prevention of Electrostatic Discharge Damage on EX Series Switches” on
page 236).
■ Ensure that you have connected the switch chassis to earth ground.
CAUTION: Before you connect power to the switch, a licensed electrician must attach
a cable lug to the grounding and power cables that you supply. A cable with an
incorrectly attached lug can damage the switch (for example, by causing a short
circuit).
To meet safety and electromagnetic interference (EMI) requirements and to ensure
proper operation, you must connect EX3200 and EX4200 switches to earth ground
before you connect them 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
“Connecting Earth Ground to an EX Series Switch” on page 141.
■ Install the power supply in the chassis. For instructions on installing a power
supply in an EX3200 or EX4200 switch, see “Installing a Power Supply in an
EX3200 or EX4200 Switch” on page 130.
To connect DC power to an EX3200 or EX4200 switch:
1. Ensure that the power supplies are fully inserted in the chassis and the screws
on their faceplates are tightened.
2. Ensure that the input circuit breaker is open so that the voltage across the DC
power source cable leads is 0 V and that the cable leads will not become active
while you are connecting DC power.
NOTE: The DC power supply in EX3200 and EX4200 switches has four terminals
labeled A+, B+, A–, and B– (see Figure 56 on page 148) for connecting DC power
source cables labeled positive (+) and negative (–). The DC power supplies for EX3200
and EX4200 switches are shipped with jumpers from A+ input to B+ input tied
together and jumpers from A– input to B– input tied together.
NOTE: The A+ and B+ terminals are referred to as +RTN and A– and B– terminals
are referred to as –48 V in “DC Power Wiring Sequence Warning for EX Series
Switches” on page 245 and “DC Power Electrical Safety Guidelines for EX Series
Switches” on page 241.
Connecting DC Power to an EX3200 or EX4200 Switch ■ 149
Chapter 11: Connecting the Switch