HP Integrity Superdome SX1000 Site Preparation Guide, Fifth Edition - HP Integ - Page 53

Facility Guidelines Electrical and Environmental Guidelines NOTE The green wire ground conductor mentioned above may be a black wire marked with green tape. Computer Safety Ground Ground all computer equipment with the green (green/yellow) wire included in the branch circuitry. The green (green/yellow) wire ground conductors should be connected to the appropriate power panel and should be sized per applicable codes (based on circuit over current device ratings). Superdome was approved by regulatory agencies around the world, and therefore requires a ground/protective earth. there are no exclusions to this regulatory approval. High-frequency grounding between IOX and Superdome is provided by the cabinet-to-cabinet signal cabling. Whenever an IOX is connected to a Superdome cabinet, low-frequency grounding between these two cabinets is provided by a ground strap. This ground strap is shipped with each IOX. Refer to the I/O Expansion Cabinet Guide for more detail. Newtwork-connected Equipment Ground The installation must provide a ground connection for the network equipment. This statement is translated into the following two languages as required: WARNING Sweden: Apparaten skall anslutas till jordat uttag, när den ansluts till ett nätverk. WARNING Denmark: Før tilslutning af de øvrige ledere, se medfølgende installationsvejledning. Raised Flooring, Signal Reference Grids, and High Frequency Grounding If a raised floor system is used, install a complete signal reference grid (SRG) for maintaining equal potential over a broad range of frequencies. The grid should be connected to power source X0 and cabinet grounds as well as to other electrical service grounds. Flat braid offers superior frequency controls to round wire. Figure 5-1 on page 46 illustrates a metallic strip grounding system. NOTE Regardless of the grounding connection method used, the raised floor should be grounded as an absolute safety minimum. For more information regarding raised computer floors, see NEC section 645-15. HP recommends the following approaches: • Excellent-Add a grounding grid to the subfloor. The grounding grid should be made of flat braid copper strips in a 2 ft. by 2 ft. manner mounted to the subfloor. The strips should be 0.032 in. (0.08 cm) thick and a minimum of 3.0 in. (8.0 cm) wide. Connect each pedestal to four strips using 1/4-in (6.0-mm) bolts tightened to the manufacturer's torque recommendation. • Better-A grounded #6 or #4 AWG 2 ft. by 2 ft. copper wire grid mechanically clamped to floor pedestals and properly bonded to the building or site ground. • Good-Use the raised floor structure as a ground grid. In this case, the floor must be designed as a ground grid with bolted down stringers and corrosion resistive plating (to provide low resistance and attachment points for connection to service entrance ground and HP computer equipment). The use of conductive floor tiles with this style of grid further enhances ground performance. NOTE The structure needs to meet all applicable safety codes and be mechanically bonded to known good grounding points. Chapter 5 45