Main Building Electrical Ground; Power Panel Ground; Computer Safety Ground; Dual Power Source Grounding - HP BL685c - ProLiant - 4 GB RAM Site Planning Manual

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For UPS products and PDUs that have permanently attached AC power cords or are directly wired to
the building power, the total combined leakage current should not exceed 5 percent of the total input
current required for the connected products.
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For UPS products and PDUs that have detachable AC power cords, the total combined leakage
current should not exceed 3.5 mA per PDU or UPS.
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. When tied to
metal chassis parts that might be touched, these ground connections protect computer room personnel
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.

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:

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
The green wire ground conductor can be a black wire with green tape (LAHJ).
Power requirements and considerations 36