Site Preparation Guide, Eighth Edition - Superdome HP 9000 Systems

Chapter 2
Electrical and Environmental Guidelines
Electrical Factors
42
Main Building Electrical Ground The main electrical service entrance equipment should have an earth
ground connection, as required by applicable codes. Connections such as a grounding rod, building steel, or a
conductive type cold water service pipe provide an earth ground.
Electrical Conduit Ground To provide a continuous grounding system, all electrical conduits should be
made of rigid metallic conduit that is securely connected together or bonded to panels and electrical boxes.
Power Panel Ground Each power panel should be grounded to the electrical service entrance with green
(green/yellow) wire ground conductors. The green (green/yellow) wire ground conductors should be sized per
applicable codes (based on circuit over current device ratings).
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.
System Installation Guidelines
This section contains information about installation practices. Some common pitfalls are highlighted. Both
power cable and data communications cable installations are discussed.
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.