HP ML115 Power basics for IT professionals - Page 16
HP ML115 - ProLiant - G5 Manual
UPC - 884962252765
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Figure 13. Typical grounding of commercial or industrial building In the United States, the National Electric Code specifies the standard grounding system resistivity value of 25 ohms. It is common practice that large industrial plants and commercial buildings require maximum 5-ohm resistivity values in the ground grid. Instrument systems generally require only 1-ohm resistivity values. When considering sensitive electronic equipment, there are three IEEE Standards that should be referenced. These standards are listed in Table 1. Table 1. IEEE power and grounding references IEEE Standard Standard Title IEEE Standard 1100-1999 IEEE Standard 142-1991 IEEE Standard 446-1995 IEEE Recommended Practice for Powering and Grounding Electronic Equipment (Emerald Book) IEEE Recommended Practice for Grounding of Industrial and Commercial Power Systems (Green Book) IEEE Recommended Practice for Emergency and Standby Power Systems for Industrial and Commercial Applications (Orange Book) 16