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A DC-powered switch is equipped with a DC terminal block that is rated for the power
requirements of a maximally configured switch.
NOTE: To supplysufficient power,terminatethe DCinput wiring on a facility DC source
capable of supplying at least 8 A at –48 VDC for EX3200 and EX4200 switches.
Tosupplysufficientpower,terminatetheDCinputwiringonafacilityDCsourcecapable
of supplying at least 60 A at –48 VDC for EX8208 switches.
Tosupplysufficientpower,terminatetheDCinputwiringonafacilityDCsourcecapable
of supplying at least 100 A at –48 VDC for EX8216 switches.
Incorporate an easily accessible disconnect device into the facility wiring. 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.
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Run two wires from the circuit breaker box to a source of 48 VDC.
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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
areaisoneinaccordancewithArticles110-16,110-17,and110-18oftheNationalElectrical
Code ANSI/NFPA70.
NOTE: Primary overcurrent protection is provided by the building circuit breaker. This
breakermust protect againstexcesscurrents,short circuits,and earth groundingfaults
in accordance with NEC ANSI/NFPA70.
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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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Forpersonalsafety,connectthegreenandyellowwiretosafety(earth)groundatboth
the switch and the supply side of the DC wiring.
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Themarkedinput voltageof –48 VDC for a DC-poweredswitch 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.
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Because the switchis a positive ground system, you must connect the positiveleadto
the terminal labeled RTN, the negative lead to the terminal labeled –48 VDC, and the
earth ground to the chassis grounding points.
Related Topics General Safety Guidelines and Warnings for EX Series Switches on page 207•
• GeneralElectrical SafetyGuidelines and Warningsfor EX Series Switcheson page235
• DC Power Disconnection Warning for EX Series Switches on page 242
• DC Power Grounding Requirements and Warning for EX Series Switches on page 243
• DC Power Wiring Sequence Warning for EX Series Switches on page 244
• DC Power Wiring TerminationsWarning for EX Series Switches on page 246
241Copyright©2010,Juniper Networks,Inc.
Chapter20: Power andElectrical SafetyInformation