
Power and Control Wiring
4.0POWER AND CONTROL WIRING
All power and control wiring must be installed by a licensed, qualified electrician. All power and con- trol wiring must comply with the National Electrical Code and all applicable local codes. Unless oth- erwise labeled, use the recommended tightening torque shown in Table 29.
The input power busbars are accessible through the front of the unit. Liebert’s 250A units have PEM nut inserts designed to allow
Cables can be installed through the top or bottom of the unit through removable conduits plates. Units with output inline panelboards are bottom exit only for output cables.
See Figures 12 through 21 for wiring entrance locations.
4.1Input and Output Power Connections
The input power connections are made to the busbars provided inside the unit (see Figures 26 through 31). These busbars are accessible through the front of the unit.
Output power connections are handled two different ways, depending on the type of distribution used. Power connections on standard units with an output breaker are made to the busbars inside the unit. These busbars are accessible through the front on 250A units and on the side on
! WARNING
Verify that all input power and control circuits are
The two input power feeds (sources) to the STS2/PDU should be from two independent sources to avoid a common source failure.
To ensure proper operation of the STS2/PDU, the two input sources must be the same nominal volt- age level and phase rotation.
For uninterrupted automatic transfer, the two input sources should be synchronized within 15 degrees.
! CAUTION
The input sources to the STS2/PDU must be
The STS2/PDU is designed for operation with
See Figures 3 through 6 for typical
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