Installation Grounding Requirement (DC Power Supplies Only)
The 650 W AC power supplies have internal grounding and so no additional grounding is required when the supported AC power cords are used.
When using the DC power supply, additional grounding of the server chassis to the earth ground of the rack is required. Screw holes for use with your grounding lugs and grounding wires are supplied on the chassis rear panel.
Note The grounding points on the chassis are sized for M5 screws. The grounding points are spaced at 0.625 inches (15.86 mm). You must provide your own screws, grounding lug, and grounding wire. The grounding lug required is a Panduit LCD10-14AF-L or equivalent. The grounding cable that you provide must be 14 AWG (2 mm), minimum 60° C wire, or as permitted by the local code.
See Figure 1-1 for the location of the grounding lug screw-holes on the chassis rear panel.
Figure 1-1 Cisco UCS C240 M3 NEBS Server Rear Panel (DC Power Supply Version)
Screw holes for grounding lugs
DC power supplies (up to two)
Wiring a DC Power Supply
Warning A readily accessible two-poled disconnect device must be incorporated in the fixed wiring. Statement 1022
Warning This product requires short-circuit (overcurrent) protection, to be provided as part of the building installation. Install only in accordance with national and local wiring regulations. Statement 1045
Warning When installing or replacing the unit, the ground connection must always be made first and disconnected last. Statement 1046
Warning Installation of the equipment must comply with local and national electrical codes. Statement 1074
Warning Hazardous voltage or energy may be present on DC power terminals. Always replace cover when terminals are not in service. Be sure uninsulated conductors are not accessible when cover is in place. Statement 1075
Note The recommended wire gauge is 8 AWG. The minimum wire gauge is 10 AWG.
Use the following procedure to connect wires to the DC power supply connector:
Before beginning this wiring procedure, turn off the DC power source from your facility’s circuit breaker to avoid electric shock hazard.
Step 1 Turn off the DC power source from your facility’s circuit breaker to avoid electric shock hazard.
Step 2 Remove the DC power connector block from the power supply. (The spare PID for this connector is UCSC-CONN-930WDC=.)
To release the connector block from the power supply, push the orange plastic button on the top of the connector inward toward the power supply and pull the connector block out.
Step 3 Strip 15mm (.59 inches) of insulation off the DC wires that you will use.
Step 4 Orient the connector as shown in Figure 1-2, with the orange plastic button toward the top.
Step 5 Use a small screwdriver to depress the spring-loaded wire retainer lever on the lower spring-cage wire connector. Insert your green (ground) wire into the aperture and then release the lever.
Step 6 Use a small screwdriver to depress the wire retainer lever on the middle spring-cage wire connector. Insert your black (DC negative) wire into the aperture and then release the lever.
Step 7 Use a small screwdriver to depress the wire retainer lever on the upper spring-cage wire connector. Insert your red (DC positive) wire into the aperture and then release the lever.
Step 8 Insert the connector block back into the power supply. Make sure that your red (DC positive) wire aligns with the power supply label, “+ DC”.
Figure 1-2 930 W, –48 VDC Power Supply Connector Block
Wire retainer lever
Orange plastic button on top of the connector