Juniper M40E Hardware Manual page 285

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Appendix A: Safety and Regulatory Compliance Information for the M40e Router
DC Power Grounding Requirements and Warning for M Series, MX Series, and T Series
Routers on page 260
DC Power Wiring Sequence Warning for M Series, MX Series, and T Series
Routers on page 261
DC Power Wiring Terminations Warning for M Series, MX Series, and T Series
Routers on page 263
M40e 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 54 A. We
recommend that the 48 VDC facility DC source be equipped with a circuit breaker rated
at 125% of the power provisioned for the input minimum, or as required by local code.
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 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.
NOTE: The router is equipped with a circuit breaker box rated at 80 A, but
even when maximally configured requires a maximum of 54 A @ 48 VDC.
NOTE: If the circuit breaker at the facility DC source is rated at less than
80 A, it (rather than the circuit breaker on the router) provides primary
current fault protection.
Run two wires from the circuit breaker box to a source of 48 VDC. Use appropriate
gauge wire to handle up to 100 A.
A DC-powered router 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 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.
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