Smart Switches

One of the first smart things I installed in my house, like most people, was a smart switch. I started using wifi switches. The family could turn on the lights like normal and they could be controlled by an app. I didn't remove their functionality but I added smartness to. The family could say Alexa......and boom the lights came on. Lots of FUN!! Now this is for us US living people. I don't know any international electrical codes and how you do things. I have heard you guys from across the pond run 220 in your switches...FUN.
In the beginning like most of us, I just bought some switches off Amazon not knowing, or caring about using an app hosted by a big company or another country. I installed it and used them for a year or two. But then when I found out about HA and moved to it. I realized that localizing all my switches, and not using a cloud in another country, was what I wanted to move to. I then tried some Shelly devices out and I liked that they were in the wall unseen. You could keep your existing light switch but have the functionality of a smart switch. Now all my light switches are flashed with Tasmota. There will be links at the end for videos explaining Tasmota, flashing devices, and all that stuff.
I have never had issues changing out light switches. In a previous life I worked as an Electrician’s apprentice with my family’s electrical contracting business. So I am way smarter than the average bear when it comes to electricity and plugs and such. When I started to change out my switches to smart ones, they needed a neutral. Ok no big deal for me as my house was built in 2005 so there are neutrals in the box already.
What is a neutral needed for? Well to not bore you with all the electrical code and theory. Basically the neutral in the light circuit is the power to the light switch. The neutral does not control the light. That's what the “switch leg” does. The neutral, in the US, is usually bundled up in the light box pushed in the back all combined together. If you aren’t using a smart switch it just lives back there and does nothing. If your house is older and its wiring is older, well it’s not easy to add neutrals.
If you use a smart switch you have to add a neutral so the smart switch can be on and get the signal for Home Assistant or whatever. Without it you would turn the light off and there would be no power for the smart switch to keep its state updated. It's just how it works. The easiest way, if you have neutrals bundled up in the box, is to just add one to the bundles already there.
Safety check here. TURN OFF the breaker. Even when I worked doing remodels and service calls I always turned the power off to the device. It’s just not worth it. Plus you don't' know if the person ahead of you knew what they were doing or even wired it correctly. The first time you get bit you will know. Also smart light switches have all their electronics so if you don’t hook it correctly you can fry the electronics. I have done that once and will never again do it.

Above are two of the type of switches you might find in your house. Those are rocker, you might have toggles. The top picture is a 3 way switch next to a regular, that's what we call it in the US. Note that dark colored screw on the side. If you find a switch with that, it is a 3 way switch. Since these are normal switches there is no need for a neutral. Now the bottom two pictures are a standard smart switch and a three-way. Note that a neutral is needed. There are some newer smart switches that don't need neutrals but most do. The three way needs a live/power and two travelers.

Open up the switch and take and take it out of the box. If it is a regular switch there will be three wires to it: a ground (bare copper, or green) and two wires. Now if the electrician that installed and did it right the power will come into the bottom of the switch. On the top of the switch it should say "TOP" The wire on the top of the switch SHOULD goes out to the light. When it is not in the switch there will be no power to that top wire. It is just a switch/ wire. If you have two, three or four switches, and the electrician did it correctly, the wires that go together might be twisted together. Look for the bundle of neutrals, if you have them, and pull them out. Add a white wire to that bundle and plug it into the neutral slot in the new switch. Now just plug the old wires your old switch needed into the new switch, or you might have to make a ring with the wire and put it under the screw, or just stab them in the holes.

Here is the wiring of a standard switch before the smart switch:

Before I go any further I check all my connections and check them again. Go turn on the switch in the breaker and BOOM, well hopefully not BOOM. If all is good the switch should work. I then turn off the breaker again and make sure all the wires are connected in the box and on the switch. I take the time and route the wires so I can put the new switch in the box. NOTE: the new switch is probably bigger and will take up more room. Put everything in the box and tighten them up. Now if the switch is not working, and it is a single switch then more than likely you have switched up the hot and the switch. So go and turn the power off and change them around.

Here are some pictures of my smart switches installed in my house.

Changing out a light switch is not that hard. I believe that anyone can do it. If you have standard wiring in your house it's easy. But if you find anything weird then you should seek professional help, an electrician, not a shrink, well maybe them also. If you need help leave me a message. I am on facebook a lot and I also MOD in Dr Zzzs channel on twitch as RasBe906.