You are probably correct on the terminology. Neutral and Ground tend to get interchanged a lot from a terminology perspective. That is why I tried to define what I was using each to represent. In my area, the Ground as you defined it is a bare wire when included in Romack but is green when run individually. Then to make matters worse sometimes you get a Red wire thrown in, or if you are dealing with a 3 way switch, sometimes both travelers are black. Nothing like making something confusing the standard way of doing things. 
LOL, yes it can be confusing.
Usually I would not be too picky about it, but in this case, most smart switches are advertised as requiring a neutral wire, so it does make a difference which wire you call neutral.
You can always connect a ground wire from the switch to the box, but if neutral wire is not there, you need to feed it from somewhere which is a much bigger job.
Randy
Understatement of the year, I would have said life threateningly wrong.
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Hi
after just reading through the whole thread, I’m still non the wiser on wall switches.
My criteria are they must not be RF controlled , a few hundred watts of SSB in to high gain antennas on 432 MHz causes mayheim with 433.8 MHz devices, so it has to be WiFi , albeit my 150W on 2320 MHz does give WiFi abit of stick , but they usually just change channel to get away from my RF
Here in the UK we do have a problem with no neutral at the switch, as the LN+E is daisychained on the ceiling roses, but the way houses are built does give an advantage, there is normally 200~300mm above the ceiling and the floor above, so you can easily put something like a sonoff
switch behind the ceiling rose. so you still have the original switches still in place, and its parallel switched.
But I still have wall lights I want HA to be able to switch, A nuetral is within 1mtr, with a wall in the way, which means annoying the wife who will insist both sides are redecorated after I chisel a small trench , plaster has been on the wall 40+years. So it wont cut cleanly and Find a two gang switch that uses proper switches or relays.
So still watching in case a suitable switch gets mentioned.
thanks
Presumably you like to watch paint dry as well
You’re not going to get a wifi switch that can use the low current dribble method that RF and the like can as it needs much power, been said many, many times previously.
No issues with neutrals in my parts even on the old houses with aluminum wiring. Guess I am lucky? These are still my favorites and easy to add other sensors to them as well. For the US style 3 ways I did Shelly1 and and another I used two switches with some Tasmota rules.
At least with paint there’s a good chance it will,
unless its the anti-theft stuff .
Luckily theres a gap in the floor under the bath upstairs , I might be able to see where the cables run, there will be a junction box up there , it may be in reach
You’re saying you have no ground/neutral in your place and these work on Wifi?
So you just have a Live(Red) and then the wire that runs to the socket(Black) and that’s all you used… not taking the Earth into account of course since it’s not necessary? So basically acting like a very basic switch which just completes the circuit. If this is all true then I’d definitely give these a try!
A ground wire is required by the National Electric Code (which virtually all local electrical codes are based), but a neutral is not required for lighting circuits.
NEC 250.134 Wiring Methods Grounding
All electrical equipment, metal boxes, cover plates, and plaster rings shall be grounded. All switches, including dimmer switches, shall be grounded.
My house was built in 1996 and I have a couple of lights, including a four-way circuit where there is no neutral in the box. I have Z-wave switches on those circuits. The Z-Wave switch (and Sonoff switches) draw practically no current themselves (RF receiver and 3v3 for the ESP, for example). For this reason you can consider it safe to use the earth ground for the neutral connection on these switches. But, it would, technically, not be within code. (I should do an experiment to see if this would trip a ground-fault interrupter breaker.)
I had never thought of using the Earth as Neutral, is this a safe option though?
Just do not do that. Earth his earth, Neutral is neutral. Do NOT mix them up.
Not sure where in the world you are, but…
- Here in Australia, that would be illegal
- As per our Wiring Rules, all socket outlets and lighting circuits must be protected by a Residual Current Device. ie: circuit breaker which trips if there is current flowing to earth. Doing what you suggest would trip the circuit.
- In the video posted by @digiblur you can see that the wall is not brick / concrete (like they are here where I live, including the internal walls) so there is no real reason why a neutral wire can’t be run to the light switch location. What are the walls like in your house? Sure it may not be the nicest / easiest task going on in your house, but it’s a lot better than doing something dodgy.
- It’s just stupid.
Please don’t use the earth as a neutral, or anything other than an earth for that matter.
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What he said.
Seriously there is some bad and dangerous stuff gets spread on this forum sometimes.
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Normally, at the breaker panel the earth (green) and neutral (white) are connected together on a ground bar. But the earth (green) wire should never carry the current of a light or appliance.
You just described what we in the U.S. call a Ground Fault Interrupter (GFCI). Any current in the ground wire will trip the interrupter. The GFCI started appearing in the U.S. National Electrical Code (NEC) around 1971. The ground fault threshold is 4mA and since the smart switch will draw about 80mA, a GFCI breaker would interrupt the power to the switch. The NEC does not require a GFCI breaker, but optionally you can use less-expensive GFCI outlets where they are required. (Bathrooms, kitchens, outdoors - anything that can get wet). After 2011, the NEC was changed to require Arc-Fault Circuit Interrupters (AFCI) breakers on all circuits in new homes, which are sensitive to the RF generated when an arc occurs. (Like the static you hear on an AM radio when there is a lightning storm nearby). AFCI does not replace GFCI where GFCI outlets are required.
I should have stated that IF YOU KNOW what you are doing, there is nothing unsafe about using an earth ground for the neutral on a smart switch. I have wired many dozens of homes, apartments and commercial buildings in my days as an electrician. I retired from that work 25 years ago but I still keep up with the electrical codes because I do all my own electrical work around the home.
If you can, just run a neutral wire to the receptacle box for the smart switch.
There’s a sonoff supplier in our country and I’ve been asking them on how they are able to have a workaround on the neutral requirement of Sonoff US T1 (our country’s power supply is 240v x 2 live wires). They sent me the diagram below and they already have few installation around the city.
I already have the sonoff us t1 and flashed it with tasmota. I haven’t tried connecting it yet since I’m not really an electricity guy and already lost two switches (Xiaomi Aqara 2-gang light switch and Broadlink TC2 due to ants).
Can anyone verify the diagram below?
I have no idea what you mean by “2 live wires”? Do you mean that a live wire comes into your switch, and then a switched live wire comes out and goes to the bulb?
Anyway that diagram is wrong on so many levels.
The whole house has two hot/live wiring system. In US, it’s usually 1 hot, 1 neutral and 1 ground right? Here, 1 live wire goes to the light and the other to the switch.
So that first wire is switched, correct? When the light switch is off, it is not at mains voltage.
If so, all light switches work like that.
The real question is whether there is also a neutral wire at the switch. The neutral is not switched.
There is some crazy stuff that goes on in the US regarding house wiring…
From what I can gather, the situation that @accelle has described is that there is the normal 110V running to the light, (and switched via the light switch) but also another live wire (unswitched) running along with those. Since it is a live and not a nuetral, you get 220V between the two. Is that what you have @accelle ? If so, I’m thinking that you could run the Sonoff between those two live wires given that they are rated to 240V… but confirm before doing so. ie: I take zero responsibility for what happens. (I live in a country where we wire things properly 
)
No, you surely get 0v between two wires that are both at 110v, unless they are out of phase.