Legrand Electrical Box Extension For Smart Home

December 6, 2022 - 3D Printing
Legrand Electrical Box Extension For Smart Home

The Problem

During the renovation of my new home I came across an unexpected problem. I can not fit smart devices like Shelly behind sockets or switches. Every electrical wall socket box I could find in the market was swallow. There are no options for electrical box expansions or deeper boxes.

The options were to either open a hole in the existing electrical box and place the automation directly in the brick or say F it I will just print it.

The Solution

I picked a Legrand electrical box which is universal (at least for Europe) and designed an expansion which you can print yourself. The expansion fits exactly the specific box very well and it will not fall of without an effort.

I printed the expansion square with PLA since the temperature is not a concern. Any smart device that will be housed behind the socket or switch will be touching the electrical box and not the printed part.


The box I selected for my house is “legrand Flush mounting box Batibox 801 51” and the expansion block will expand your box by 16cm/6.30inch in depth.

I picked that box as it can accommodate both clamp and drywall sockets/switches. You can probably install that box in drywall but i’m an expert on that. 

I have uploaded the design in cults3d and you can find it here if you want to support me:

The fit is not too tight or too loose, to me feels just right. You can always use some super glue to secure it into place.

3d design of the expansion module


After installing a standard EU socket plenty of space was left for a first or second generation of Shelly and for extra cables required for automation instalment.

If you need any general alterations in height/depth or anything else in the design please let me know and I will upload another variant as soon as I can.