Emerson FPC Manuel D’Utilisation

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.

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.