HP Integrity rx7620 Server - User Service Guide, Sixth Edition

3. Check that the braid contact on each end of the ground straps consists of a terminal and
connection hardware (a 0.25 in. (6.0 mm) bolt, nuts, and washers).
4. Check that the braid contact connection points are free of paint or other insulating material
and are treated with a contact enhancement compound (similar to Burndy Penetrox).
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. For installation procedures, see the appropriate installation guide.
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.
Environmental Elements
The following environmental elements can affect server installation:
• Computer room preparation
• Cooling requirements
• Humidity level
• Air conditioning ducts
• Dust and pollution control
• Metallic particle contamination
• Electrostatic discharge (ESD) prevention
• Acoustics (noise reduction)
Computer Room Preparation
The following guidelines are recommended when preparing a computer room for the server:
• 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.
186 General Site Preparation Guidelines