Dumb Question about Smart Switches

I have been reading about smart switches, this article mentions load control switches (master, should be one per light) and add-on switches (non-load controlling switches).

Let's say I want to put the load control switch into the ceiling (hidden) and just use the add-on switches as the 'physical' switches.

In the context of a 'dumb light', is my understanding correct:

  • not withstanding the need for a power supply, the add-on switches wirelessly control the 'master' switch in the ceiling?

  • putting the master switch in the ceiling is a dumb idea and I should used something designed for that purpose?

If my understanding is correct, can someone please point me in the direction of a device that I can put in my ceiling and the corresponding wall switches to control it.

  • Note that if you're in the US, code requires that all junction boxes be permanently accessible with nothing more than a screwdriver to remove the cover plate. You're not allowed to bury any wiring junctions behind something that must be disassembled to get access to it. How you going to fix the device when it dies or if a wire comes loose?
    – FreeMan
    Feb 27 at 15:46

2 Answers 2


in the ceilling you need a relay with a controlling board of somekind. For the "remote" switches one microcontroller reading a momentary or latching switch. the remote MCU sends a message (MQTT for example) to the relay MCU that activates or deactivates the load.

This is just one simple way to do it.


  • 1
    José - thanks for chiming in! To be honest I could probably build this with my Arduino stuff - I really just want to know what the actual device is called and perhaps get a link to a product that's designed for this purpose... due to the clutter in results Google is unhelpful :( Nov 21, 2017 at 21:37
  • 1
    Hi SlowLearner. If you are in Australia the best is for you to see Jonathan Oxer website and youtube channel (Superhouse.tv). He is an expert in this kind of stuff and he also sells some speacially designed PCBs for light switches, for example, so they can fit in your wall plates. In his site he explains in detail how to assemble whatever you need in home automation. Definitely a guy to follow if you're in to this stuff.
    – José Rosa
    Nov 29, 2017 at 9:45
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    If you want to build something of your own, it will depend on your skills with microcontrollers but i would suggest you use one D1 Mini NodeMCU for each end - one controller attached to the wall switch and one controller attached to a relay wich switches the load to the lights.
    – José Rosa
    Nov 29, 2017 at 9:51
  • 1
    Hi José - yes in Sydney, thanks will check it out. Not so keen to build my own - don't mind messing about with wifi controlled fairly lights etc but for a permanent installation I much prefer something 'robust' ;-) Nov 29, 2017 at 10:11

In 2024, you can buy these off the shelf. I am using Fibaro z-wave devices, but any Z-wave or Zigbee device will do the job. On most of them, there is no master device, you can configure them for multi-way switches. And these devices are designed to fit behind your wall switch.

They do require either a zwave or zigbee server or a stick to plug into your desktop. You can also link them to Alexa.

Two examples -

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