I use BS170 MOSFETs for applications like this because it can handle .5A on and 60 volts off. We have an A/C unit at work with a drip pan that drains into a large bucket. The bucket would overflow and make a huge mess before I built an alarm for it. I built it on a scrap piece of single sided copper clad, about 1" x 3". The piezo alarm was a 2 lead type from Radio Shack. Other parts are a 1M resistor, any small capacitor to RF bypass the gate, a 9V battery clip with leads, and some scrap telco cable. The battery is just taped to the ckt board underneath the piezo buzzer, I just put a little hook in the cable so that the end hangs about two inches into the bucket. By cutting the wires to 2 different lengths, before stripping them back 1/4", you avoid the accidental contact. The MOSFET is much beefier than CMOS and you can lay out the whole board with a Sharpie. You could even use a razor knife or Dremel to isolate the traces. The only critical spacing would be for the piezo buzzer. Parts cost is < $10. Joe
Looks like there are plenty of choices out there. Steve has also suggested a small 'dam', made from a bead of caulk, be used to make the water pool just a bit where it enters, helping ensure that the sensor gets wet.
For all I know, the silly things are on the shelf at the local hardware store. This is closing the barn door after the horse has escaped, but what can you do?
I had the same problem years ago. I installed a sump pump in a below grade barrel under a grate at the bottom of the stairs. I suppose an alarm would also be nice, but the pump completely solved my flooding problem. This is not a cheap solution, but it removed the stress of worrying about the leaves and melting snow every year. I also lowered the grade outside so that the concrete (and grate) were about 4" below the basement grade.
Today's adventure started with a splash ... and maybe someone out there has a solution!.....
So ... I'm asking the vast ECN membership .... is there any way to set an alarm for this condition, to notify the homeowner there's a problem before they're wading in it?...
I don't usually do this... But this might be a simple solution, the slightest amount of water will set this off, and it's pretty loud:
GOOD GRIEF! Has it been there, in OUR store, all along?
Bill, I am humbled .... and I bet it's perfect for this place. Best of all, I can set it exactly where I know the water will be next time.
BTW ... there are some business lessons in this little mess.
We called the alarm company .... after looking through their stuff, the guy admitted that they DID have the capability, he even had a sensor in his shop, but he can't recall ever installing one. Hello missed sales!
The cleaning crew's opinion as to what had to be done / should be done, etc., seemed to change dramatically whether they thought the bill would be paid by us, or the insurance company. This really undermines the customers' confidence. Maybe part of the problem is that they see the insured and the insurance carrier as two different 'customers.' What I think should have happened, at the earliest stages of the clean-up, was that the lead man should have immediately sat down with the occupants and explained, in detail, what needed to be done, what his plan of action was, and the expected expense. If there was anything the customer could do to help (say, bringing in fresh air or raising the thermostat), that should have been mentioned.
Just as important, they should have explained whatever secondary damage was anticipated - such as damage to baseboards and fixing vent holes placed in the walls - exactly who gets to fix it, and when that might happen.
There has been no visit by any adjuster; the claim was flat-out denied. I am not surprised.
I assume there is only a standard homeowners' policy. Flooding is one thing that is typically excluded from insurance policies; 'flood insurance' is handled exclusively by the Federal Government.
What is covered by your usual policy is flood and water damage that is incidental to, that is caused by, some other insured event. For example, a broken water pipe.
