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Location Considerations
5
2.0 LOCATION CONSIDERATIONS
The STS2/PDU should be placed in a clean, cool and dry location. The 250A unit without an output
cabinet requires only front access for installation and maintenance. Both front and side access are
required for installation and maintenance of 400-800A units and 250A units with output cabinet. The
output cabinet comes factory installed or either the right or left side depending on how it was ordered.
It cannot be moved from one side to the other in the field.
Adequate space is required above the unit for conduit (if configured as such) and cooling air flow. This
section provides specific information for these considerations.
The unit is designed with top and bottom cable terminations to allow maximum flexibility in its
installation. Units with output inline panelboards are bottom exit only. If bottom cable entry and exit
is used, sufficient cable bending space must be provided by a raised floor or a floor stand.
For dimensions of each unit, see Figures 7 through 22. If your unit is equipped with an optional key
lockout switch, see Figures 13 through 21 for the location of that switch.
2.1 Recommended Minimum Service Clearances
The recommended service clearances are at the front and side, if equipped with output cabinet. The
minimum service clearance required by the National Electrical Code (NEC) Article 110-26 is
36 in. (91cm) for units with voltages up to 150V to ground and 42 in. (107cm) for units with voltages
over 150V to ground. Clearance of at least 18 in. (46cm) is required above the unit for cooling air flow.
2.2 Heat Output
The unit produces minimal heat during normal operation.
2.3 Operating Environment
The unit is designed to be installed indoors where the ambient air temperature is in the range of
32° to 104°F (0°C - 40°C) with a relative humidity of 0% to 95% non-condensing, up to an altitude of
4000 feet (1200 meters).
Table 2 Heat output
Switch Size
Heat Output
BTU/Hr (kW)
250A 12,590 (3.69)
400A 20,140 (5.90)
600A 30,200 (8.85)
800A 40,270 (11.80)