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Five (5) wires should be run from thermostat subbase to the 24V terminal board in the unit. A five conductor, 18 gauge copper, color-coded thermostat cable is recommended. The connection points are shown in Figure 8: TABLE 3 THERMOSTAT WIRE SIZE Maximum Transformer Distance VA FLA Wire Gauge In Feet 55 2.3 20 gauge 18 gauge 16 gauge 14 guage 12 guage 45 60 100 160 250 TABLE 4 WALL THERMOSTAT AND SUBBASE COMBINATIONS Thermostat Subbase Predominate Features 8403-002 T87F3111 8404-003 Q539A1220 1 s