Dc Power Electrical Safety Guidelines - Juniper SRX5400 Hardware Manual

DC Power Electrical Safety Guidelines

DC Power Electrical Safety Guidelines
The following electrical safety guidelines apply to a DC-powered services gateway:
A DC-powered services gateway is equipped with a DC terminal block that is rated for the power
requirements of a maximally configured services gateway. To supply sufficient power, terminate the DC
input wiring on a facility DC source capable of supplying at least 30 A @ -48 VDC for the system. We
recommend that the 48 VDC facility DC source be equipped with a circuit breaker rated at
40 A (-48 VDC) 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.
Run two wires from the circuit breaker box to a source of 48 VDC. Use appropriate gauge wire to handle
up to 40 A.
A DC-powered services gateway 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.
For personal safety, connect the green and yellow wire to safety (earth) ground at both the services
gateway and the supply side of the DC wiring.
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