A technician is installing a 3 ton cooling system with a 15 kW electric furnace. How many conductors are required for wiring the thermostat?

In a typical setup involving a 3-ton cooling system paired with a 15 kW electric furnace, the number of conductors needed for wiring the thermostat is based on the functions that need to be controlled.

Electric heating systems usually require at least two conductors to facilitate the control signals from the thermostat to the electric furnace: one for the heating and one for the cooling function. In this case, since there is a cooling system involved, it also requires a conductor to manage the cooling operation. Therefore, the basic requirement would be for two conductors for separate signals to the furnace and the air conditioning system.

However, to optimize the operation and provide additional functionalities, the thermostat often needs a common wire (C) for continuous power, especially in smart thermostats that require a constant power supply. This increases the total number of conductors to ensure all features of both the heating and cooling systems can be utilized efficiently.

Thus, when considering the basic operational requirements for both heating and cooling systems, along with accommodating for a common connection, a total of four conductors is necessary. Therefore, in this scenario, four conductors are required for the complete application, ensuring both systems are effectively controlled by the thermostat.