A.O. Smith DSE-5 THRU DSE-120 Installation And Operaion Manual page 16

3-1 PHASE CONVERSIONS
In the case where the unit is phase convertible and it has only one contactor, jumper wires (provided) must be added according to
the phase of the supply voltage. See the diagram below. For single-phase connection, jumpers A-C and B-D must be added. For
three-phase connection, jumper B-C must be added.
3-1 PHASE CONTACTOR JUMPER CONFIGURATION
FIGURE 1 FIGURE 2
3 PHASE CONNECTION
1 PHASE CONNECTION
SMALL COMMERCIAL WIRE DIAGRAM
300-600V / 3PH
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