HP ProLiant SL270s HP ProLiant SL Servers Planning Guide - Page 28

Power panels located in close proximity to the computer equipment should also be connected to the site grounding grid. Raised floor "high-frequency noise" grounding IMPORTANT: Regardless of the grounding connection method used, the raised floor should be grounded as an absolute safety minimum. If a raised floor system is used, the floor must be designed as a signal ground grid that maintains an equal potential over a broad band of frequencies. To accomplish this, observe the following guidelines: • Use a raised floor system where the stringers are bolted to the pedestals. • Select floor components that have a corrosion-resistant plating to provide low resistance connection points to other components and to computer cabinets. • Connect a 2/0 copper conductor to every other pedestal around the perimeter and to the equipment grounding system of the building. • Bond all metal pipes that enter or leave the raised floor area to the 2/0 perimeter ground. • Bond each row and column of the floor grid to the 2/0 perimeter ground. • Bond any I-beams that penetrate the raised floor to the pedestals. • Connect the opposite corners of equipment cabinets to the pedestals with #12 stranded wire. • Where the cabinets are bolted together in rows, bonding two corners at opposite ends of the row is sufficient. • Bonding straps should be 70 cm (24 in) or less in length. If a bolted-stringer raised floor system is not used, the alternate methods that may provide acceptable results include the following: • Use a grounded #6 AWG minimum copper wire grid that is clamped mechanically to floor pedestals and bonded properly to the building or site ground. • Add a grounding grid made of copper strips mounted to the subfloor. The strips should be 0.8 mm (0.032 in) thick and a minimum of 76 mm (3.0 in) wide. Connect each pedestal to four strips using 6-mm (0.25-in) bolts tightened to the manufacturer's torque recommendation. Power requirements and considerations 28