Updating to a Smarter Light Switch

I’ve got to the stage where my Gen 1 LightWaveRF light switches just don’t cut it any more. Not having any feedback from the light switch itself has meant that creating automations around them is near impossible. The final straw has been the death of one of my slave switch units. The Gen 1 range is no longer available from LightWave and replacing them all with the Gen 2 LightWave range is prohibitively expensive. A quick browse around their online shop at a like-for-like replacement of my current setup (Hub, 4× 1-gang, 2× 2-gang, 2× 1-gang slave, 1× relay) clocks in at the £800 mark.

The Wish List

I began listing the requirements that any replacement solution would need and settled on the following criteria:

• Either be a replacement switch or solution that sits within / behind the ceiling rose; I don’t like smart bulbs
• If a switch, it must be compatible with UK wiring. (No neutral available in the switch’s back box)
• Provide dimming at the switch; not just on / off
• Still usable if my home automation system is unavailable
• Report its status to allow for use in automations
• Not be horrendously expensive

The Search for the Perfect Light Switch Begins

Given that I’d be taking the Lightwave switches out, my initial search was for replacement light switches. The first stumbling block however, as predicted, was not having a neutral wire at the switch. This quickly cut down my options drastically. The next hurdle was to find something that would allow for 2-way switching (referred to as 3-way in the US). Factor in dimming at the light switch, the requirement to still work if any hubs or networking fail and it honestly looks like LightWave is the only available option in the UK.

The Search Hits a Dead End…

I had to start broadening my search and look at non-switch solutions. I came across a number of cheap WiFi Dimmers from various brands but all with almost identical spec and using the same Cloud app to control them. It turns out a company called Tuya are responsible for this range of devices. They offer companies the opportunity re-brand their products with their own name . More research showed that they consisted of an ESP8266 to handle the WiFi connection connected to a second MCU to do the actual dimming.

The good news was that some clever developers had already done the hard work and reverse engineered the modules. Using a tool called Tuya-Convert allows you to flash the onboard ESP module. I ordered one and when it arrived flashed it with Tasmota to remove the need for third party cloud-based apps to control it. A script has to be added in Tasmota to handle the dimming, due to the internal setup of the device. Mains voltage is sent through the switch when activated and through a pulse counter connected to the ESP8266. The ESP then sends serial information to the secondary MCU to control the dimming.

Unfortunately whilst testing the unit it would intermittently stop responding whilst using the switch to dim. This was usually followed by Tasmota crashing and the unit restarting, causing the bulb to turn off. After several days of frustratingly fruitless tinkering I started looking for another option.

Shelly to the Rescue

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I then came across the Shelly range of devices, in particular the Shelly Dimmer 2. This ticked all of the boxes in terms of my above criteria, and with a few added bonus features too. Especially useful is the “Night Mode” which allows you to set a time range and a brightness limit. This is great when you switch on a light at night as you aren’t blinded by it being at full brightness. I ordered a single unit to test and quickly appreciated how easy it was to setup and configure and just how flexible it was too. There is an integration in Home Assistant allowing for really easy setting up of automations. If you prefer to use MQTT then there is an option for that as well.

A few weeks later I took the plunge and ordered a unit for each of the lights and also a replacement relay for controlling the bathroom extractor fan.

Retractive Light Switch Options

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A retractive light switch is needed to provide dimming at the switch, and not just in-app. This is the sort where you press it and it bounces back to the original position. There is a real lack of non-industrial focussed retractive switches and most of them have the image of a bell, or a “Push To Exit” screen printed on them as they are typically used for door access, not for residential purposes. After a bit of a search I came across the relatively cheap Schneider Electric Lisse 10AX from Screwfix. They don’t officially do a 2 or 3 gang version of the light switches, but the only difference between the normal on-off position and the retractive ones, is the addition of a spring. You can get creative and transplant them really easily as the internal mouldings are all exactly the same.

£170 on Shelly dimmers and £30 on switches later, I have a near-enough like for like replacement. Granted the light switches aren’t quite as pretty, but I can live with that given the additional features gained over the old ones!