Juniper Networks MX480 - Manual (Page 295)

MX480 DC Power Electrical Safety Guidelines and Warnings
• MX480 DC Power Electrical Safety Guidelines on page 271
• DC Power Electrical Safety Warnings for Juniper Networks Devices on page 272
MX480 DC Power Electrical Safety Guidelines
The following electrical safety guidelines apply to a DC-powered router:
• A DC-powered router is equipped with a DC terminal block that is rated for the power
requirements of a maximally configured router. To supply sufficient power, terminate
the DC input wiring on a facility DC source capable of supplying at least 58 A (32 A per
feed) @ –48 VDC for the system. The 48 VDC facility DC source should be equipped
with a circuit breaker rated at 40 A (–48 VDC) minimum. Incorporate an easily
accessible disconnect device into the facility wiring. In the United States and Canada,
the 48 VDC facility should be equipped with a circuit breaker rated 40 A (–48 VDC)
or a minimum of 125% of the power provisioned for the input in accordance with the
National Electrical Code in the US and the Canadian Electrical Code in Canada. Be sure
to connect the ground wire or conduit to a solid office (earth) ground. A closed loop
ring is recommended for terminating the ground conductor at the ground stud.
• Run two wires from the circuit breaker box to a source of 48 VDC. Use appropriate
gauge wire to handle up to 50 A.
• A DC-powered router that is equipped with a DC terminal block is intended for
installation only 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 should protect against excess currents, short circuits,
and earth faults in accordance with NEC ANSI/NFPA70.
• 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 router and the supply side of the DC wiring.
• The marked input voltage of –48 VDC for a DC-powered router 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 router is a positive ground system, you must connect the positive lead to
the terminal labeled
RETURN , the negative lead to the terminal labeled –48V , and the
earth ground to the chassis grounding points.
Related
Documentation
DC Power Supply Electrical Specifications for the MX480 Router on page 301 •
• Calculating Power Requirements for MX480 Routers on page 285
271 Copyright © 2013, Juniper Networks, Inc.
Appendix A: Safety and Regulatory Compliance Information for the MX480 Router