Site Preparation Guide, Second Edition - HP Integrity cx2620 Server
Missing-phase and low-voltage
detectors
Shuts equipment down automatically when a severe power
disruption occurs. For peripheral equipment, these devices
are recommended but optional.
Online uninterruptible power
supply (UPS)
Keeps input voltage to devices constant and should be
considered if outages of one-half cycle or more are common
Refer to qualified contractors or consultants for each situation.
Distribution Hardware
This section describes wire selection and the types of raceways (electrical conduits) used in the
distribution system.
Wire Selection
Use copper conductors instead of aluminum, because 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 (electrical conduits) (LAHJ)
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 heatsink
for the wires.
Any of the following types may be used:
• Electrical metallic tubing (EMT) thin-wall tubing
• Rigid (metal) conduit
• Liquidtight with RFI shield grounded (most commonly used under raised floors)
• Armored cable
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.
Grounding Systems
HP systems are tested and certified only with grounding systems in which a neutral return path
and a protective earth are separate conductors without any inserted impedances. Additionally,
protective earth and return neutral are shorted together at the X0 bonding junction on the
secondary side of the newly derived power source.
IT Power System This product has not been evaluated for connection to an IT power system
(an dc distribution system having no direct connection to earth according to IEC 60950). A server
requires two methods of grounding:
• Power distribution safety grounding
• High frequency intercabinet grounding
Power Distribution Safety Grounding (LAHJ)
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.
Power distribution systems consist of several parts. HP recommends that these parts be solidly
interconnected to provide an equipotential ground to all points.
26 General Site Preparation Guidelines