Juniper EX4300 Hardware Manual page 327

Chapter 27: Electrical Safety Guidelines and Warnings
Ensure that the polarity of the DC input wiring is correct. Under certain conditions,
connections with reversed polarity might trip the primary circuit breaker or damage
the equipment.
For personal safety, connect the green and yellow wire to safety (earth) ground at both
the device and the supply side of the DC wiring.
The marked input voltage of –48 VDC for a DC-powered device is the nominal voltage
associated with the battery circuit, and any higher voltages are only to be associated
with float voltages for the charging function.
Because the device is a positive ground system, you must connect the positive lead to
the terminal labeled RTN, the negative lead to the terminal labeled –48 VDC, and the
earth ground to the device grounding points.
Related General Safety Guidelines and Warnings on page 265
Documentation
General Electrical Safety Guidelines and Warnings on page 297
DC Power Disconnection Warning on page 306
DC Power Grounding Requirements and Warning on page 307
DC Power Wiring Sequence Warning on page 308
DC Power Wiring Terminations Warning on page 310
Connecting DC Power to an EX2200 Switch
Connecting DC Power to an EX3200 Switch
Connecting DC Power to an EX4200 Switch
Connecting DC Power to an EX4300 Switch on page 176
Connecting DC Power to an EX4500 Switch
Connecting DC Power to an EX4550 Switch
Connecting DC Power to an EX4600 Switch
Connecting DC Power to an EX6200 Switch
Connecting DC Power to an EX8200 Switch
Connecting DC Power to an EX9204 Switch
Connecting DC Power to an EX9208 Switch
Connecting DC Power to an EX9214 Switch
Connecting DC Power to an OCX1100 Switch
Connecting DC Power to an XRE200 External Routing Engine
Connecting DC Power to a QFX3500, QFX3600, or QFX3600-I Device
Connecting DC Power to a QFX5100 Device
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