HP ProLiant SL270s HP ProLiant SL Servers Planning Guide - Page 27

Main building electrical ground, Conduit bonding, Power panel ground, Computer safety ground

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Power distribution systems consist of several parts. HP recommends that these parts be solidly interconnected to provide an equipotential 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. Conduit bonding Construct all electrical distribution systems of metallic conduit that is connected together securely or bonded to panels and electrical boxes 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 overcurrent device ratings). NOTE: The green wire ground conductor can be a black wire with green tape (LAHJ). 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 overcurrent device ratings). Dual power source grounding With dual power sources, both sources must have the same ground reference. Otherwise, an electrical potential could exist that could be hazardous to personnel and might cause performance issues for the equipment. Because the dual power sources often originate from two different transformers or two different UPS devices, use the same ground reference point to ground the secondary of each transformer or UPS device. Measure the voltage potentials from ground pin to ground pin of these sources. Voltage levels that are measured above 3.0 V might be hazardous to personnel or cause equipment performance issues and must be corrected before placing the equipment in service. Cabinet performance grounding (high frequency ground) Some safety power distribution wires are too long and too inductive to provide adequate high-frequency return paths. Signal interconnects between system cabinets might need high-frequency ground return paths in addition to the safety or power distribution system 50-60Hz grounding system. HP recommends the use of a properly installed SRG, also bonded to the 50-60Hz grounding system. WARNING: Do not use a cabinet-to-floor ground strap in place of a properly installed safety (50-60Hz) grounding system, nor in place of a properly installed SRG. An improperly installed grounding system can present a shock hazard to personnel. Power requirements and considerations 27

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Power requirements and considerations
27
Power distribution systems consist of several parts. HP recommends that these parts be solidly interconnected
to provide an equipotential 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.
Conduit bonding
Construct all electrical distribution systems of metallic conduit that is connected together securely or bonded
to panels and electrical boxes 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 overcurrent device ratings).
NOTE:
The green wire ground conductor can be a black wire with green tape (LAHJ).
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 overcurrent device ratings).
Dual power source grounding
With dual power sources, both sources must have the same ground reference. Otherwise, an electrical
potential could exist that could be hazardous to personnel and might cause performance issues for the
equipment.
Because the dual power sources often originate from two different transformers or two different UPS devices,
use the same ground reference point to ground the secondary of each transformer or UPS device. Measure
the voltage potentials from ground pin to ground pin of these sources. Voltage levels that are measured
above 3.0 V might be hazardous to personnel or cause equipment performance issues and must be corrected
before placing the equipment in service.
Cabinet performance grounding (high frequency ground)
Some safety power distribution wires are too long and too inductive to provide adequate high-frequency
return paths. Signal interconnects between system cabinets might need high-frequency ground return paths
in
addition to
the safety or power distribution system 50-60Hz grounding system. HP recommends the use of a
properly installed SRG, also bonded to the 50-60Hz grounding system.
WARNING:
Do not use a cabinet-to-floor ground strap in place of a properly installed safety
(50-60Hz) grounding system, nor in place of a properly installed SRG. An improperly installed
grounding system can present a shock hazard to personnel.