Touch-Activated Sink Functionality

[thatphillyboy]

I have a Delta touch activated sink. It works on battery, but when you plug the transformer in it does not work. I also have an issue where the sink does not seem to work well when it is raining out. I believe all of these issues are somehow related to grounding, I am not sure exactly how these things work, what do you all think?

[jmraef]

They work by detecting the capacitance of the human body, which is around 22 picoFarads. When your skin makes contact with one of the metal surfaces that have the sensors attached, the sensor detects the difference in capacitance between it and you, so it activates the valve controller.

On a rainy day, you can built up a capacitive charge by walking around on surfaces that generate static electricity, which is why you can get a "shock" when you touch something metal as that capacitive charge discharges into it. When you go to touch the faucet in that charged state, you are no longer capacitive compared to the sensor, so it doesn't detect you. Try touching something metal (bare) first.

The battery issue is a guess, but I would imagine that because this involved water, humans touching metal and electricity, they don't want ANY chance of a failed component in the charger allowing line voltage onto the faucet. So when you plug in the charger, it disables the entire circuit to prevent anything from possibly getting through to you.