Sump Pump Water Sensor

[nyjumpee]

Hello! Relatively simple question. . .how far can I extend the wire on the water sensor on my sump pump water level alarm? Right now, it's about 6 feet, but I'd like to have the water sensor in our cottage and place the actual alarm in my house, which is about 75' away. I'd also like to possibly add an external flashing light mounted on the cottage so someone can tell at a glance if there's a flood situation in our cottage. Thanks in advance for your help!

 

[MikeMl]

If the voltage at the alarm output of the sump pump is 120VAC, it is a bad idea to be running it all over the place. I would use it to control a relay with a 120V coil, and then use a low-voltage circuit (12V or 24V from a plug-in power supply) to extend the alarm function to the other house.

 

[nyjumpee]

Thanks for the reply! The alarm is not connected to the pump. . .it's actually just an inexpensive battery operated 9V alarm ~ kind of like a smoke alarm with an external sensor that's connected to the alarm by a thin 2 conductor wire. . .I'm just worried that if I extend the wire too far, it won't work the way it was originally intended. . .any thoughts? Thanks again!

 

[MikeMl]

Running the wire to the other house shouldn't effect the operation of the alarm. Is the alarm triggered by a float switch like I have in the bilge of my boat? If so, put the alarm unit in your house, and use a two-conductor low-voltage wire to reach the float switch. Your biggest problem will be burying the cable, or running it overhead. UV sunlight overhead, or moisture in the ground will damage the wire, and be the hardest problem to deal with.

Any chance you have a spare pair in a phone cable running between the cottage and the house? Is there a direct burial conduit? An unused coax run?

When I build a garage some distance from my house, I planned ahead, and buried two separate PVC conduits. One for 240VAC for power to the garage. The other for low voltage circuits (which shouldn't be run in the same conduit as 120/240V) which had a CAT5 cable for computer, another for phone, intercom, alarm, and a75Ω TV Coax run.

 

[nyjumpee]

Long Run resistance?

Thanks again Mike! I actually do already have a CAT5 cable running from the cottage to the house that's not currently in use, so maybe I can just tap into that for the "extension" wire. My main concern is that this is just a simple, cheap water sensor. . here's a picture of the exact unit that I have:
**broken link removed**

I'm guessing that the way the sensor works is it detects a change in resistance which then triggers the alarm. . .just don't know that if that long of a run would affect the way the cheap little sensor is supposed to work. . .

I guess I'm wasting more time thinking about it than just wiring the thing to see if it works or not! Thanks again for your input and I'll letchya know how it turns out!

 

[MikeMl]

Pick a pair in the CAT5 cable and short the distal end. Use your Ohmmeter to measure the loop resistance from the proximal end. Now go add a resistor equal to the measurement (a few tens or low hundreds of Ω?) in series between the sensor and the alarm box (requires cutting a wire). Test it to see if it still works. If yes, you are good to go. I'll predict it will work just fine.

My other prediction is that you may experience some false alarms when there are electrical storms in the area. Remoting the loudspeaker out of the alarm box (a low impedance circuit) may be a better way to go.

 

[nyjumpee]

Thanks, Mike. . .makes sense to me. . . will do. . .thanks again for all of your help and input!