Alternate Grounding Configuration, Non-Isolated; Figure 7 Alternate Grounding Configuration, Non-Isolated - Liebert 610 Series Installation Manual

6.4

Alternate Grounding Configuration, Non-Isolated

A few applications in this power range have 208 VAC input and output, and a connected load consist-
ing of multiple Power Distribution Units (PDUs), panelboards, switchboards or other items of load
equipment which do not have isolation transformers.
Notice in Figure 7 that the UPS system main input and bypass input are connected to a grounded-
wye service. In this configuration, the UPS system is not considered a separately derived source.
The UPS module output neutral and the load neutral are solidly connected to the building service
neutral, which is bonded to the grounding conductor at the service entrance equipment.
Figure 7 Alternate grounding configuration, non-isolated
This arrangement may be used for systems with 208 VAC input and output. However, it does not pro-
vide any isolation or common-mode noise attenuation for sensitive loads. For this reason, this config-
uration is not a preferred installation method.
NOTE
If there is a 4-pole Automatic Transfer Switch (ATS) between the service entrance and the UPS,
this configuration cannot be used. Refer to 6.3 - Preferred Grounding Configuration With
Isolated Bypass to determine a suitable configuration.
Configuring Your Neutral and Ground Connections
17