Attwood Electronic Bilge Switch 12V 4801 ~7 Attwood s S3 electronic bilge switch is the industry answer to broken mechanical switches, jammed float mechanisms and ever annoying excessively cycling pump. The S3 Series bilge pump switch incorporates a proprietary Solid State electronic Sensing Technology to detect bilge water levels and trigger pump activation more consistently, more reliably and for a significantly longer working life compared to traditional mechanical float switches. The S3 can be hooked onto the side of the Tsunami series bilge pumps, can be mounted to the floor of the bilge or mounted to the side wall of a stringer without any additional brackets.