Sewer Pump Alarm?

You can also check out the Monoprice 15270 zwave plus sensor which has an external dry contact sensor that can be configured with a N/C or N/O option.



RBoy, your solution is basically the same as Ron’s correct? I would still have to have a rely in there somewhere? Or does the device you link somehow eliminate that step?

Assuming the relay is wired in - Would the inclusion of the relay effect the reliability of the “light” alarm in any way. This is basically a luxury, so I don’t want to do anything that would impact the reliability of the system. For example, if the relay failed would the light then also fail?

Following the wires from A1 and A2 I see they go into that white Schneider box where I see NC and NO terminals meaning normally open and normally closed which is what the contacts that others have posted accept. Using a multimeter I would measure voltage there putting one contact on A1 and NO and also A2 and NO when it’s alarming to see what voltage is because you don’t want to fry a contact sensor. If it’s low voltage you could leverage the NC terminals that aren’t used for a contact sensor.

Thank you everyone for your replies and thoughts. I will get my multimeter on those terminals this weekend and see what they are reading.


I remember @JDRoberts has some devices in his catalogue that you can put on control panels/lights to detect the light goes on/off. I tried digging in last years post but… finding just one post in the thousands JD contributes is just mission impossible:)

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The Fibaro motion sensor would be worth trying as it also detects both light and vibration. You might be able to find a place where you could put it where the siren would set off the vibration alarm. And you could get a separate trigger for the light level. It’s Z wave plus, so the range will be pretty good. And it’s quite small and battery-operated. So I think that would be the first one I would try. No wiring required, you just have to figure out the best place to stick it.

To make it work with smartthings, make sure you get the Z Wave model, not the HomeKit model.

If you are in the North American region, Homeseer has a light sensor intended to detect when the indicator light on a dumb appliance comes on or changes color. So it may also work, but it’s not available on the European frequency. It’s battery operated, so no wiring is required.

If those two don’t work, then you could try one of the various in-line devices. There’s an FAQ that lists quite a few, including the ones already mentioned:

FAQ: List of devices with dry contact input from external sources

It’s just a question of whether you’re going to be able to get enough signal out of the box to reach the next device on your network. :sunglasses:

Again. Thank you everyone for your thoughts. Looks like through these various options, I might be able to get something to work.

I appreciate all your thoughts and suggestions.

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Dry contact sensors can only detect when the contact has been closed or opened externally. It could via a magnet or relay. Some devices have outputs which can be connected to dry contact sensors. For example you have an Aux alarm, not 100% sure but may be that could be a proxy for connecting to the dry contact sensor if they don’t have any voltage associated with them and are connected to a relay internally.

I don’t think we’re talking about the same thing here. :thinking:

A contact sensor typically detects a “closed” event when the magnet piece is moved close enough to the other piece that the magnet can pull the thin metal “reed” inside the other piece of the sensor into position.

”Dry Contacts”: on the other hand, are connecting points on a device which complete a circuit when an external device is electrically active. The device with the dry contacts can be pretty much anything: one very popular one is the Mimolite. Which doesn’t do anything else: it’s designed specifically as a bridge to add zwave communication to dumb devices.

As it happens, there are a couple of contact sensors which also have dry contacts, but that was just a manufacturer decision. Because these typically cost quite a bit less than the mimolite, people often use them for simple on/off reports, particularly for low voltage devices like a doorbell.

The mimolite is a much more robust device. Not only can it handle somewhat higher voltage, you can set it to detect with a range rather than just on/off. Or to count pulses. And you can use it as a relay to turn off a 120v device as well, something you can’t do with the ecolink sensor, for example.

So it’s just a coincidence that there are “contact sensors” with “dry contacts”— the word “contact” is being used two different ways there. :sunglasses:

For the OP:

As to what happens if the bridge device fails…the dry contacts attachment is just a physical loop spliced into the existing circuit. That part can’t really fail unless the wire becomes physically detached from the contact post, so it shouldn’t be an issue even if the radio communication fails.

The mimolite or other control devices could be more of a problem if they randomly open or close the relay. But that’s an optional feature.

In any case, I’d still recommend trying the Fibaro multisensor first. No wiring required, so even total failure shouldn’t change the pump’s function in any way. :sunglasses:

2022 update

The mimolite is no longer being sold at retail, but there are a number of other devices now available. See the faq:

FAQ: List of devices with dry contact input from external sources

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Hi everyone. I know this thread has been idle for a year now but was hoping to get some help regarding my situation which is very similar to Stephen’s. Have a sewer ejector pump with panel inside my garage. Goal is to have notification through smartthings if the pump fails and the alarm float makes contact. The alarm float goes back to the panel and sets off an audible alarm and light on the panel. There’s power from the float alarm so i don’t believe i’d be able to use an ecolink contact sensor without frying it. I do have a mimolite and zooz zen16 laying around. Would either of these work for my use case?

In the control box I see that everything works with the general AC power.
The easiest thing I see is to use a zigbee or zwave switch that allows an input from the manual switch connected to the line and would place it in the junction box that you have below the box.
I put a photo as an example of the zigbee samotech MS-104Z, it is cheap and works well in samartting.

Connections to make, if you can, check this with a multimeter:

  • the supply of the switch line (L) to terminal nº 5, red wire comes from the alarm fuse.

  • The supply of the Neutral Switch (N) to the terminal above the right white wire, which also has to go to the common of the alarm and pump pilot on the front panel.

  • The input of the manual switch S1 of the switch to terminal No. 6, Violet wire that goes to the alarm pilot and horn switch. It must comes from the float switch, white wire.

  • Take these three cables to the junction box under the control panel and connect them to the switch terminals N, L and S1 as in the switch in the example photo.

  • The switch output terminals can be left free, it is an isolated 16A relay or you can use it to connect something if you want.

  • I would pair the switch to the hub before connecting it and you would already have a switch status event change when the alarm is activated or deactivated and you can send notifications or perform actions.

  • You can test the circuit by joining terminals 5 and 6, this would simulate the closed float switch contact.

Remember to disconnect the general power to work safely :wink:

Hi Mariano. Thank you for taking the time to write this up. I checked online for the device you recommended samotech MS-104Z… and can’t seem to find it here in the US. Is there another similar item that could be used in the same capacity that I can find here in the US?

I found this on amazon… looks like it has the same terminals so would this work?

The sonoff mini is not valid for this.
It does not admit voltage on the input contacts of the switch.

The samotech, here are not available now on Amazon, the last ones I bought in AliExpress, they took a little longer to come.

Moes zigbee switch is similar and available in Amazon Spain

In zwave the Aotec nano and the fibaro single switch 2 are worthwhile. They are more expensive, but they are good.

The fibaro has the possibility of adjusting parameter 20 so that the closed switch input is always an “On” event and open is an “off” event.

I do not know if aotec nano have this function.

Fibaro, now, official dth works in cloud.
Aotec, i don’t know if works local. Other users could help you in this.
Samotech and moes work local with stock dth zigbee switch.

Did you find a switch that could be useful to you?
When you have it, do not hesitate to ask if you have any questions or need something

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Unfortunately no not yet. I am going away for a week on vacation so will decide on one of your recommendations while away. Most likely the aeotec since it seems to be the most widely available and when I get back I plan to hook it up. Will definitely reach out if I get stuck and let you know how it all works out. Thanks again for your help with this.

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You can also use the ecolink sensor post n° 2, solution with external contact input and a relay.
Connecting the neutral, white wire, and terminal 6, violet, to relay coil common and 115 vac input, and connect the relay contacts outputs, Common and N.O. to the external input of the sensor ecolink.
So when the float contacts closed, the relay will activate and send a sensor closed event and vice versa.
I have seen the links and there is stock on
You have time to think about it.
Enjoy your vacations

Hi Mariano. Just got back from vacation and have the relay in hand. Wanted to clarify which connections go where? Im a visual learner so put together this kinda diagram. Would you mind showing me how the connections should be made?


  • Connect the white of the 0v relay to the neutral, according to the photo it must be that. To make sure, if you don’t have a multimeter, connect a light bulb with two wires between neutral, white, and terminal 5 of the strip, red.
  • The black of the 115v relay to terminal 6 of the strip, purple and wite, which is the return of the float switch.
  • the common C of the relay to one terminal of the sensor and the normally open terminal NO to the other terminal.

The Sensor, I think is put without the magnet so that it shows open, and closed when close the relay.

Remember, work safe, removing the general current


Hooked it up according to your instructions and it works flawlessly. Thank you so much!



I’m glad it works well.
To propose a little improvement, I would put the relay in the box below, with the sensor. :wink:
Good idea of @rontalley
Regards and have a nice weekend