An electric motor spins a fan and oil pump simultaneously. Air from the fan is directed into a blast tube. At the end of the tube is a nozzle spraying the oil that the pump has put under high pressure. Released from the pressure at the nozzle, the oil atomizes into a fog and is ignited with an electric spark. The spark is generated by a transformer that boosts the voltage upwards of 10,000 volts or more. Watching the ignition is an electric eye known as a cad cell. Current generated by the fire on the window of the cell is conducted to a burner-relay and keeps the relay engaged and the burner motor running. If the fire goes out, the burner will shut down to prevent a build-up of unburned fuel and an explosive condition.