Checking the grounding of the system and redundant AC-power switch

Ensure that you understand how to check the grounding of a system and the optional redundant AC-power switch feature.

About this task

DANGER

Multiple power cords. The product might be equipped with multiple power cords. To remove all hazardous voltages, disconnect all power cords. (L003)

To test the grounding of a system node, follow the steps for the specific system configuration that you are using. Before you start, confirm that you know the model type of your system, and whether you are using redundant AC power. Determine the location of the signal cables that are attached to the system.

When you are asked to test the grounding continuity, use your local procedures to initiate the test. The test is successful if the measured resistance is 0.1 ohm or less.

Attention: Some electrical circuits can be damaged if the external signal cables are present at the node while it is undergoing a grounding test.

1. Ensure that the node is powered off. See MAP 5350: Powering off a node.
2. Disconnect all signal cables from the node, which includes the following cables:
   • The Fibre Channel cables
   • The Ethernet cable or cables
3. If redundant AC power is used, turn off any node that is being supplied from the redundant AC-power switch. Then, remove the power cable to this system from the redundant AC-power switch.
4. Disconnect both input power leads from the site power distribution units
5. If redundant AC power is used, test the grounding continuity between a conductive area on the frame and the ground pin on the plug of the main power cable of the redundant AC-power switch. If the test is successful, test the grounding continuity between a conductive area on the frame and the ground pin on the plug of the backup power cable of the redundant AC-power switch. Both tests must be successful.
6. Initiate one of the following procedures after you complete testing the grounding continuity, depending on the outcome of the test.
   • If the test is successful, reconnect any cables that were removed.
   • If the test was not successful, ensure that all cables are securely connected. If the test still fails, test the individual system components. Before you test the individual components, remove all cables from the components. If any component test fails, replace the component. After you test each component and replace any failing ones, repeat the complete system test by returning to step 1.
     Test the components in the following order:

     1. The node, from the frame to the ground pin of the input power receptacle
     2. The redundant AC-power switch, if used, from the ground pin of the main input power receptacle to the ground conductor of the output power receptacle, and from the ground pin of the backup input power receptacle to the ground conductor of the output power receptacle
     3. The redundant AC-power switch main input-power cable, if used, between the two ground conductors of the cable
     4. The redundant AC-power switch backup input-power cable, if used, between the two ground conductors of the cable