Emerson Static Transfer Switch User Manual

The Liebert STS2 should be placed in a clean, cool and dry location. The Liebert STS2 requires only 

front access for installation and maintenance. Back or side access is not required. 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. If bottom cable entry is used, sufficient cable bending space must be provided by a raised 

floor or a floor stand.
For dimensions of each unit, see Figures 5, 6 and 7 in section 7.0 - Installation Drawings on 

page 18. If your unit is equipped with an optional key lockout switch, see Figures 8 through 10 for 

location of that switch.

The recommended service clearances are at the front of the unit. The minimum service clearance 

required by the National Electrical Code (NEC) Article 110-26 is 36 in. (91 cm) for units with voltages 

up to 150V to ground and 42 in. (107 cm) for units with voltages over 150V to ground. Clearance of at 

least 18 in. (46 cm) is required above the unit for cooling air flow.

The unit produces minimal heat during normal operation.

The unit is designed to be installed indoors where the ambient air temperature is in the range of 32° 

and 104°F (0°C and 40°C) with a relative humidity of 0% to 95% non-condensing, up to an altitude of 

4000 feet (1200 meters).

100 amp

2,711 (0.80)

250 amp

4,680 (1.37)

400 amp

6,972 (2.04)

600 amp

10,520 (3.08)

800 amp

13,777 (4.03)

1000 amp

17,390 (5.09)