HP rp7400, Hardware Manual

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Specify Grounding Requirements
47
Specify Grounding Requirements
Grounding systems
HP rp7400 servers require two methods of grounding:
• Power distribution safety grounding
• High frequency intercabinet grounding
NOTE Some of the grounding requirements described here may differ outside of North America.
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.
Power distribution systems consist of several parts. Hewlett-Packard recommends that these parts be solidly
interconnected to provide an equal-potential ground to all points.
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 All electrical conduits should be made of rigid metallic conduit, Flex-T conduit,
or liquid-tight conduit that is securely connected together or bonded to panels and electrical boxes, so as to
provide a continuous grounding system.
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).
Computer equipment 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 parity-sized (based on circuit over current device ratings).
Cabinet interconnect grounding
Signal interconnect between system cabinets requires high frequency ground return paths. Connect all
cabinets to site ground.
NOTE In some cases power distribution system green (green/yellow) wire ground conductors are too
long and inductive to provide adequate high frequency ground return paths. Therefore, the
customer may choose to provide a ground strap for connecting the system cabinet to the site
grounding grid (customer-supplied). Installation of this ground strap is optional and there is a
chance that it may cause ground loops.
Power panels located in close proximity to the computer equipment should also be connected to site grounding
grid. Methods of providing a sufficiently high frequency ground grid are described in the next sections.