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Installation Instructions
15
Figure 10 Low voltage control junction box connections, typical
Figure 11 Main input junction box connections, typical
1.3.3 System Grounding
The performance and safety of any power conditioning system depend on proper grounding.
Figure 12 shows the typical grounding arrangements for the Liebert FPC.
Equipment Grounding
Equipment grounding is primarily for safety. Correct implementation of grounding also enhances
equipment performance. All power feeders must include equipment grounding means as required by
the NEC and local codes.
An insulated ground conductor is recommended to be run in each feeder conduit. Ground conductors
must be at least the minimum size per NEC Table 250-66. Larger wire sizes may be used for
increased system performance.
If the input power feeder conduit is used as a grounding conductor, adequate electrical continuity
must be maintained at all conduit connections.
!
CAUTION
Using isolating bushings in a metal conduit run can be a safety hazard and is not
recommended.
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Building
Interface
Relay
Factory-supplied
low-voltage control cable
A
B
C
N
G
Customer input
power connection
3-phase, 3-wire + GND
for units with transformer
3-phase, 4-wire + GND
for units without transformer
Factory-supplied
input power cable
assemby
NOTE: Parallel cables
are used on units with
higher-ampacity
Neutral busbar and wire
furnished on units
without transformer