Superdome Servers - I/O Expansion Cabinet Guide, Fifth Edition

Appendix B
Site Requirements
Power Requirements
207
Wire Selection
Use only copper conductors instead of aluminum, as aluminum’s coefficient of expansion differs significantly
from that of other metals used in power hardware. Because of this difference, aluminum conductors can cause
connector hardware to work loose, overheat, and fail.
Raceway Systems
Raceways (electrical conduits) form part of the protective ground path for personnel and equipment.
Raceways protect the wiring from accidental damage and also provide a heat sink for the wires.
Any of the following types may be used:
• Electrical metallic tubing (EMT) thin-wall tubing
• Rigid (metal) conduit
• Sealtight (for humid environments)
Building Distribution All building feeders and branch circuitry should be in rigid metallic conduit with
proper connectors (to provide ground continuity). Conduit that is exposed and subject to damage should be
constructed of rigid galvanized steel.
Raised Floor Application A cable trough is not required for the IOX installed in a computer room that has
a raised floor. The power drops and interface cables from the equipment are routed down through the panel
pull section, through a grommet-protected opening (beneath the floor level), and under the floor panels.
Nonraised Floor Application A cable trough may be required when the IOX is installed in a computer
room that does not have a raised floor. The power drops and interface cables from system are routed down
through the panel pull section, out through a grommet-protected opening, and into the cable trough.
The cable trough connects to the bottom of the power panel. It should be sized to hold all cables and
receptacles for the power drops that come from the server and peripheral power panels and for the power
cables and plugs that come from the peripheral cabinet(s).
While the length of the cable trough may vary from one site to the next, the width and height must be
compatible with the computer system cable trough.
NOTE The cable trough should be recognized by safety agencies as a ground conductor. It should be
sturdy enough to walk on.
Grounding Systems
The IOX requires two methods of grounding:
• Power distribution safety grounding
• High frequency intercabinet grounding
Power Distribution Safety Grounding
The power distribution safety grounding system consists of connecting various points in the power
distribution system to earth ground using green (green/yellow) wire ground conductors. Having these ground
connections tied to metal chassis parts that may be touched by computer room personnel protects them
against shock hazard from current leakage and fault conditions.