In a four-wire primary system, which component does the blue wire connect to?

The blue wire in a four-wire primary system typically connects to the transformer. In such a system, wires are color-coded to ensure proper connections and function. The transformer is a critical component that converts the incoming voltage to the appropriate level needed to power the heating system efficiently. Typically, it reduces higher voltage from the power supply to a lower voltage that can be used by control components, such as the burner motor or safety devices.

Understanding the function of these components within the context of the entire heating system is essential for troubleshooting and maintaining oil heating equipment effectively. The transformer plays a vital role in ensuring that all other components receive the correct voltage and operate as intended.