HP Integrity rx7620 Site Preparation Guide, Fourth Editon - HP Integrity rx762 - Page 50

General Site Preparation Guidelines Electrical Factors System Installation Guidelines This section contains information about installation practices. Some common problems are highlighted. Both power cable and data communications cable installations are discussed. NOTE In domestic installations, the proper receptacles should be installed prior to the arrival of HP equipment. Refer to the appropriate installation guide for installation procedures. 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 can cause serious problems, such as erratic equipment operation. A high-resistance connection can overheat and cause 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. When equipment vibration is present, lockwashers must be used on all connections to prevent connection hardware from loosening. 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. 36 Appendix B