Juniper QFX5100 Hardware Manual page 235

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Copyright © 2017, Juniper Networks, Inc.
A DC-powered device that is equipped with a DC terminal block is intended only for
installation in a restricted-access location. In the United States, a restricted-access
area is one in accordance with Articles 110-16, 110-17, and 110-18 of the National Electrical
Code ANSI/NFPA 70.
NOTE: Primary overcurrent protection is provided by the building circuit
breaker. This breaker must protect against excess currents, short circuits,
and earth grounding faults in accordance with NEC ANSI/NFPA 70.
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.
General Safety Guidelines and Warnings on page 187
General Electrical Safety Guidelines and Warnings on page 209
DC Power Disconnection Warning on page 216
DC Power Grounding Requirements and Warning on page 217
DC Power Wiring Sequence Warning on page 218
DC Power Wiring Terminations Warning on page 220
Connecting DC Power to an EX2200 Switch
Connecting DC Power to an EX2300 Switch
Connecting DC Power to an EX3200 Switch
Connecting DC Power to an EX3400 Switch
Connecting DC Power to an EX4200 Switch
Connecting DC Power to an EX4300 Switch
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
Chapter 21: Safety and Compliance Information
215