[avlengineer]

I work on an IT/network team. We are wanting to make sure that our switching/router hardware is properly grounded in our com room racks. Cisco is our primary vendor who recommends that you should never rely on the electrical circuit to provide adequate grounding. Instead they recommend a secondary earth ground from the hardware chassis to the building ground. Today we mostly are using just the third prong of AC circuit. It would be a substantial cost and effort to setup the NEBS grounding as is recommended. I am trying to better understand the power surge risks.

This following information is taken directly from cisco documentation:

http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/hardware/Chassis_Installation/Cat6500/02prep.html#wp1080884

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System Grounding
You must install a NEBS-compliant system ground as part of the chassis installation process. Chassis installations that rely only on the AC third-prong ground are insufficient to properly and adequately ground the systems.

Proper grounding practices ensure that the buildings and the installed equipment within them have low-impedance connections and low-voltage differentials between chassis. When you include NEBS-compliant system grounds, you reduce or prevent shock hazards, greatly reduce the chances of equipment damage due to transients, and substantially reduce the potential for data corruption.

Without proper and complete system grounding you run the risk of increased component damage due to ESD. Additionally, you have a greatly increased chance of data corruption, system lockup and frequent system reboot situations by not using a system (NEBS compliant) ground.



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Caution Installations that rely solely on system grounding using only an AC third-prong ground run a substantially greater risk of equipment problems and data corruption than those installations that use both the AC third-prong ground and a properly installed system (NEBS compliant) ground.

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Questions:
1) The above information suggests using a low impedance connection. Is there any way that I could measure the impedance of the current ground?

2) Any feedback/experience would be greatly appreciated?