Detect water with a Micro Maestro?

I am building a system to monitor my basement sump pit & pump. I need a way to get data into my computer, and I think the Micro Maestro might be able to do it. Right now I’m just trying to monitor two things - high water condition and when the sump pump is running. I have a float switch I am using for a high water condition. That float switch kicks on a backup pump, so when the switch is triggered there is a 12v signal I can detect. I think I just need to reduce it to 5v and then I should be able to detect it with the Micro Maestro? I could also have it flip a relay instead, if necessary.

For detecting the pump running, I thought I would just look for water in the pipe. That way it will tell me if either pump is running.

Can the Micro Maestro detect water directly? I just did a test by using my volt meter and trying to use a bowl of water as a conductor. With a 13v supply, I only got about a 1v voltage drop. So if I were to set one of the Micro Maestro’s channels as an input, then run leads from it to my discharge pipe, could I detect when water is being pumped out? When the pipe is empty, the Micro Maestro should see 0v. When there is water, it should see something like 4-5v, right?



It should be possible to directly detect water - water does definitely conduct some electricity - but I would worry about how well it will keep working over time, as corrosion, dirt, algae and whatever else build up. The conductivity is also strongly dependent what salts you have in your water. Connecting to the 12V signal sounds a lot easier; you just need to make a suitable voltage divider to get the signal down below 5V. Make sure that you measure the maximum voltage that might come out of that output - if it is intended to power the motor directly, it might be a lot higher when the motor is disconnected, for example.


Thanks for the reply Paul. I will use the 12v signal to indicate a high-water condition, but I also want to monitor when the main 120v pump runs. It runs every 5 minutes or so. The 12v signal will just be to indicate when something is really wrong. I want to log the main pump for statistical purposes, and for peace of mind when I’m not home (I will be hooking this data up to a webpage that I can check remotely). So I thought an easy way to do that would be to detect when there is water in the discharge pipe. The water is actually pretty clean, but I’m sure some corrosion will still happen. But I think I only need to send something higher than 0v to the Micro Maestro, so I imagine it would work a long time even with some corrosion.

Unless you have a different idea on how to detect when the 120v pump is running? What about wrapping a wire around one of the 120v leads? Could I run the leads from that coil to the Maestro and detect something?

Also - yes the 12v signal is directly used to power the backup pump, so will there be a voltage surge when the switch (and pump) turns off? The switch will turn off the pump and the signal to the Micro Maestro at the same time (its the same switch), so that might prevent a voltage spike from reaching the Micro Maestro?

Thanks for the help.