DC Power Electrical Safety Guidelines

This topic applies to hardware devices in the EX Series product family, which includes switches and the XRE200 External Routing Engine.

This topic also applies to hardware devices in the QFX Series.

• A DC-powered device is equipped with a DC terminal block that is rated for the power requirements of a maximally configured device.

  Note: To supply sufficient power, terminate the DC input wiring on a facility DC source that is capable of supplying: Minimum of 7.5 A at –48 VDC for EX2200 and EX3300 switches Minimum of 8 A at –48 VDC for EX3200 and EX4200 switches Minimum of 50 A at –48 VDC for EX6210 switches Minimum of 60 A at –48 VDC for EX8208 switches Minimum of 100 A at –48 VDC for EX8216 switches Minimum of 7 A at –48 VDC for QFX3500 devices

  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.

• Run two wires from the circuit breaker box to a source of 48 VDC.
• 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.