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Installation Instructions
18
1.3.5 Output Power Connections
Output circuit breaker(s) and/or panelboards with ground and neutral provisions are provided inside
the unit for connecting load(s) as required. (See Figures 5 through 8.)
Flexible output distribution cables for use in data processing areas under a raised floor are optional
and may be factory-supplied. Cable lengths and layout should be well-planned:
• Cable access—Cable routes should follow aisles between equipment. This will facilitate access to
cables for installation, routine inspection and alterations.
• Cable length—Measure the distance to the load equipment following right-angle paths, rather
than diagonally or directly. Always measure to the extreme far side of the equipment with respect
to the unit to ensure adequate cable length.
• Air circulation—Prevent restriction of airflow under the raised floor by running the flexible con-
duits flat on the subfloor, in parallel paths.
For best performance, the Liebert FPC should be installed as close as practical to the load.
Initial system output loading should be between 50% and 75% of rated capacity. This allows the addi-
tion of loads without immediately investing in another power conditioner. The high partial-load effi-
ciency of the FPC permits such sizing without imposing an energy-use penalty during initial
operation.
Balancing of loads is good design practice on any 3-phase system. Accordingly, each distribution panel
is load-balanced at the factory, based on output branch circuit breaker sizes. All additions to the sys-
tem should be arranged so as to preserve this balance.
For phase-shifted, multi-output units, to ensure proper harmonic current cancellation, the loads
should be balanced across the multiple outputs as well. For example, with a dual-output unit, the
loads should be balanced across the six output phases. For a quadruple output unit, the loads should
be balanced across the 12 output phases.
Code Compliance—All output cables and connections must comply with the NEC and all other
applicable codes.
Padlock-Off Provisions—All output cables without receptacles that are hard-wired to the load
equipment must be equipped with a padlock-off accessory for the output circuit breaker. The
padlock-off accessory is to be used to lock-out and tag the circuit breaker when service is performed on
the hard-wired load equipment in accordance with OSHA safety rules.
!
WARNING
Verify that all incoming line voltage (power) and low-voltage (control) circuits are
de-energized and locked out before installing cables or output breakers or making
connections, whether in the junction box or in the unit.
Verify that incoming line voltage circuits are de-energized and locked out before installing
output breakers and cables.