What is the typical resistance in ohms for a cad cell?

A cad cell, which is short for cadmium sulfide photocell, plays a crucial role in the operation of oil-fired burners. Its primary function is to detect the presence or absence of a flame. The typical resistance of a cad cell in bright light conditions is approximately 400 ohms. This resistance level is important because it ensures that the electrical circuitry connected to the cad cell can accurately sense the flame, enabling the burner to operate safely and efficiently.

When the burner is not operational or the flame is extinguished, the resistance can rise significantly, indicating a lack of flame. Therefore, the value of around 400 ohms reflects the cad cell's designed sensitivity to light, which allows it to effectively fulfill its role within the burner system. Understanding the typical resistance helps technicians troubleshoot and maintain heating systems that rely on this technology, ensuring they operate correctly and safely.