HP Integrity Superdome SX1000 User Guide, Sixth Edition - HP Integrity Superdo - Page 149

Site Preparation Electrical and Environmental Guidelines Wiring Connections Expansion and contraction rates vary among different metals. Therefore, the integrity of an electrical connection depends on the restraining force applied. Connections that are too tight compress or deform the hardware and causes it to weaken. This usually leads to high impedance causing circuit breakers to trip. CAUTION Connections that are too loose have a high resistance that cause serious problems, such as erratic equipment operation. A high resistance connection overheats and sometimes causes fire or high temperatures that can destroy hard-to-replace components such as distribution panels or system bus bars. Wiring connections must be properly torqued. Many equipment manufacturers specify the proper connection torque values for their hardware. Ground connections must only be made on a conductive, nonpainted surface. Lockwashers must be used on all connections to prevent connection hardware from working loose. Data Communications Cables Power transformers and heavy foot traffic create high energy fields. Route data communications cables away from these areas. Use shielded data communications cables that meet approved industry standards to reduce the effects of external fields. Data cables that are run externally to a metal fire enclosure must have a minimum fire rating of VW-1 or VW-4 or better. Environmental Elements The following environmental elements can affect a Superdome server installation: • Computer room preparation • Cooling requirements • Humidity level • Air conditioning ducts • Dust and pollution control • Electrostatic discharge (ESD) prevention • Acoustics (noise reduction) • Zinc whisker control Computer Room Preparation The following guidelines are recommended when preparing a computer room for a Superdome server system: • Locate the computer room away from the exterior walls of the building to avoid the heat gain from windows and exterior wall surfaces. • When exterior windows are unavoidable, use windows that are double- or triple-glazed and shaded to prevent direct sunlight from entering the computer room. • Maintain the computer room at a positive pressure relative to surrounding spaces. • Use a vapor barrier installed around the entire computer room envelope to restrain moisture migration. • Caulk and vapor seal all pipes and cables that penetrate the envelope. • Use at least a 12-inch raised floor system for the most favorable room air distribution system (underfloor distribution). Chapter 5 137