15 AMP WW Bilge Pump Switch - Durable Marine Grade for Boats, Yachts, and Watercraft

I've been using these Water Witch sensors since owning my first sailboat back in the 80's. I've only had one give me a problem over all this time and the company replaced it under warranty. The thing I like about these sensors is how they don't rely on moving parts to work like most bilge alarms/switches. Also they are very small.How I use them is to wire them to a standard self contained bilge pump that has a float switch inside. The way I connect the wires the automatic bilge pump (that contains its own float switch) will come on if/when the water rises to about 3/4". With my wiring the pump will come and a buzzer will sound.I attach the Water Witch to the output hose of the automatic bilge pump and so if the bilge pump doesn't come on (such as if its internal float switch fails) and the water level reaches the Water Witch at about the 1.5 inch level . . . then the Water Witch sensor/switch will supply power direct to the bilge pump and also sound the buzzer. Using this arrangement provides me with a built-in backup.