Introduction: Shelly Power Consumption Alarm Signal

This instructable must be performed by someone who has good skill as electrician.
I don’t take any responsibility about dangers to people or things.

In Italy the regular power contract is for 3KW, and if your power consumption goes over this limit for a while the power counter will cut-out the electricity, so you must reach the power counter and switch it on again, this is quite annoying especially during night. Since lately this was happening very often in my house I decide to make the overload visibile, so that you can switch off something before the power goes off.


1 of Shelly RGBW 2
1 of Shelly EM
1 of 50A current transformer
1 220Vac to 24Vdc transformer
1 RGBW led strip

Step 1: Connect Shelly RGBW 2

First of all I connected the Shelly RGBW 2 to the led strip, using the 220Vac to 24Vdc transformer according to the Shelly diagram as shown in the picture.

When all the electrical connections were completed, I configured the Shelly device in order to connect it to my network.
I’m not explaining how to add the Shelly device to your network since this steps are already well explained in the Shelly documentation that you can find here or in the box of your device.

Step 2: Adjust Settings of Shelly RGBW 2

When the RGBW 2 was properly connected and I was able to see it in my Shelly app, I adjust its settings as in the picture.

I made some test by changing the colors and the intensity to see if everything was ok.

Step 3: Place Shelly RGBW 2 and Led Strip

Whan I was sure that the Shelly RGBW 2 was working properly, I installed it in the plasterboard ceiling in the middle of my living room so that the light can be visible almost from everywhere in my small house.

Step 4: Connect Shelly EM and 50A TA

I installed the Shelly EM in the main distribution panel of the house, then I connected the Shelly EM to the main power 220Vac as shown in the Shelly documentation, and then I clamped the current transformer (aka TA) to the main power phase coming inside the house.

Step 5: Adjust Setting of Shelly EM

When the EM was properly connected and I was able to see it in my Shelly app (once again instruction here or in the box of the device), I adjusted its settings as in the picture.

I made some test by switching ON and OFF some devices around the house to see if everything was ok.

Step 6: Create Scenario to Switch on RGBW Led Strip to RED Color

I created a new scenario to check if the power consumption goes over than 3KW.
In that case I switch on the red color on the RGBW led strip.
I also turn ON the output relay of the Shelly EM (it has an internal relay that I didn’t connect), this is very important because I use it like a flag to know that the RGBW led strip was switched on by this scenario.
I will explain better in the next step.

Step 7: Create Scenario to Switch OFF RGBW Led Strip

I created another scenario as shown in these pictures. This scenario will turn OFF the led strip only if the power consumption is less than 2900W and the Shelly EM output (my flag) is ON.
The scenario will switch OFF the led strip, set it to warm white (so that when I will ask to Alexa to turn on that light will not be red, because the colors setting is retained on the Shelly RGBW 2) and switch OFF the internal relay (my flag).

Now you can understand why I need a flag: because I want to trigger the switch OFF scenario only if I had a Switch ON scenario before (flag TRUE). After the execution of the switch OFF scenario I clear the flag.

Step 8: Pratical Example

Here you can see a video while the system is working.
In the first video you will see the led light turning ON and OFF,
In the second video you will see first what's happening on the Shelly EM side, and then on the RGBW 2 side.
Note that when the power is greather than 3KW the output on the EM will turn ON, and when is less then 2.9KW the output will switch OFF.
Also note that on the RGBW 2 side the led color is going back to normal after the execution of the "alarm".
That's all, it’s a quite simple project but it’s very useful for me and I hope it could be useful for someone else as well.