Liebert Series 600T Preferred Grounding Configuration, 208 VAC input and output

GROUNDING

ELECTRODE

PER NEC 250-24

Figure 4. Preferred Grounding Configuration, 208 VAC input and output

7.4.Preferred Grounding Configuration, 208 VAC Input and Output, Non- Isolated Load, Wye-Connected Service

A few applications in this power range have 208 VAC input and output, and a connected load consisting of multiple Power Distribution Units (PDUs), panelboards, switchboards or other items of load equipment which do not have isolation transformers.

Notice in Figure 4 above that the UPS module main input and bypass input are connected to a grounded-wye service. In this configuration, the UPS module 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.

This arrangement is typical for systems with 208 VAC input and output. However, it does not provide any isolation or common-mode noise attenuation for sensitive loads.

Liebert Series 600T UPS, 65-225 kVA, Single Module 11