The sensor cable carries the ultraviolet intensity signal from the sensor in the reactor wall back to the control panel. It runs in a wet, warm location and its connector is a common failure point; a degraded cable or connector shows as a drifting, noisy or dead intensity reading with a sensor that is itself sound. Pin count and length both identify the cable — check the connector on the existing sensor before ordering. This is the cable for the DVGW and ÖNORM certified sensor variant. Those two certifications — the German and Austrian drinking-water schemes — apply to the sensor and its measuring chain as a whole, so on a certified plant the specified cable is part of what is certified and a general-purpose substitute is not equivalent.