Cisco 4948 Installation Guide - Page 36

System Grounding Chapter 2 Preparing for Installation 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. 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. Table 2-1 lists some general grounding practice guidelines. Table 2-1 Grounding Practice Guidelines Environment Electromagnetic Grounding Recommendations Noise Severity Level Commercial building is subjected to direct lightning strikes. High For example, some places in the United States, such as Florida, are subject to more lightning strikes than other areas. All lightning protection devices must be installed in strict accordance with manufacturer recommendations. Conductors carrying lightning current should be spaced away from power and data lines in accordance with applicable recommendations and codes. Best grounding practices must be closely followed. Commercial building is located in an area where lightning storms frequently occur but is not subject to direct lightning strikes. High Grounding best practices must be closely followed. Commercial building contains a mix of information technology equipment and industrial equipment, such as welding. Medium to High Grounding best practices must be closely followed. Existing commercial building is not subject to natural environmental noise or man-made industrial noise. This building contains a standard office environment. This installation has a history of malfunction due to electromagnetic noise. Medium Grounding best practices must be closely followed. Determine source and cause of noise if possible, and mitigate as closely as possible at the noise source or reduce coupling from the noise source to the victim equipment. Catalyst 4948E and Catalyst 4948E-F Switch Installation Guide 2-8 OL-21561-02