Single-state relays are used to detect the presence of electrically conductive liquids at the level of the mounted flood probe. When dry, the relay contact remains in position 7-4. When the probe is flooded with liquid (i.e. the probe electrodes are short-circuited), the relay contact is switched to position 7-8. After the liquid level drops (the probe electrodes are opened), the relay contact returns to position 7-4.