Vertiv | Liebert
®
PPC
™
User Manual | Rev. 6 | 03/18 | 10
1.3.1 Input Power Connections
If the unit is furnished with junction boxes, input power connections are made as detailed in 1.3.2 - Junction Box
Installation (If Used).
If junction boxes are not furnished, the input power feeder is connected to the input power lugs or blocks located
inside the unit. (See Figures 6, 8, and 10.)
To minimize disturbances caused by other loads in the building, the 3-phase power input to the unit should be
supplied directly from the service entrance or other power source (a dedicated power feeder).
The input feeder circuit should be sized in accordance with the NEC and any local building codes to assure the
feeder’s ability to safely carry the system’s full load current, including losses.
Input feeder conductors should be sized for no more than 2% voltage drop. If operation at undervoltage
conditions for extended periods of time is desired, the input feeders must be oversized.
Typical conductor size data is shown in Table 2. All connections must comply with the NEC and all other
applicable codes.
For units with a transformer, the main input feeder should consist of 3-phase conductors and one (safety)
ground conductor (3W + G).
For units without a transformer, the main input feeder must consist of 3-phase conductors, one neutral and
one (safety) ground conductor (4W + G).
WARNING
Risk of electric shock. Can cause injury or death.
Verify that all incoming line voltage (power) and low-voltage (control) circuits are de-energized and
locked out before installing cables or making connections, whether in the junction box or in the unit.
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