Review on 🛥️ Attwood 4201-7 Float Switch with Cover: Bilge Pump, 12- & 24-V, CE Rated, Compact Design - 4 ¼ Inches L x 3 7/8 Inches W x 1 3/8 Inches H by Jose Mcdaniel

I bought this float switch to replace an old broken float switch that contained mercury. The Attwood float switch contains no mercury, it is a purely mechanical switching function. I bought this version with a lid because my boat's hold is clogged with hoses and the lid protects the float from tampering. It was easy to install and seemed to work fine at first glance. However, there were a few times when I visited my boat and found that the water level in the hold was high enough for the float switch to activate, but for some reason the float switch was not working. About a year later this happened enough times that I decided I couldn't trust the Attwood float switch, so I removed it and replaced it with a different brand float switch that seems to work fine. I tried it in a bucket of water. Mechanically, the float switch still worked and the electrical contacts still worked. The problem was that at the very moment when the swimmer tries to activate the switch, there is little mechanical resistance and the buoyancy provided by the swimmer is sometimes insufficient to overcome this mechanical resistance. What happens is that the water level keeps rising but the float doesn't rise any higher ("stuck") and the circuit never activates the bilge pump. If the water in the bilge is sloshing, it is very likely that the float switch will get enough pressure to trip each time. However, if the water is calm and slowly rising, it's possible that the float switch isn't working when it should. This is not caused by air pockets under the cover. There is a small vent hole at the top of the lid, but this can become clogged with bilge debris. I already drilled a vent hole to make it bigger to keep air from getting under the lid. In general the design is good but for something as important as a bilge pump float switch the device is not reliable enough.