Neutral for WiFi Switch

[scorpiouk]

hi all,
Live in a new build and it has 3 wires for the lights, so have been able to add a few wifi switches. as the Neutral has been present.

Fitting one tonight to the garage lights, these were added by a local electrician shortly after the build. There is no neutral present on this light switch.
Its next to a socket in the garage, so thought id be smart and take a Natural from the socket and feed it into the light switch..

Connected the Sonoff as follows:

Old SW Sonoff
Comx2 - L in
N - Nin
L1 - L1out
L1 - L2out (light at the other end of the garage)

Switch the power back on and immediately tripped the RCD. Have I missed something or wired it incorrectly. Presumably its the borrowed Neutral. I thought Neutrals were common at the CU...

Any Help appreciated..

 

[flameport]

Any connection to neutral must be part of the same circuit.
It is not acceptable to connect part of one circuit to another one.

In this case the RCD tripped.
Without an RCD, the interconnection would result in both circuits remaining energised when one of them was disconnected at the consumer unit.

 

[scorpiouk]

Thanks for the quick reply.
So I either need to find the Neutral in this lighting circuit or could I take one from the CU?

 

[ban-all-sheds]

Or you could reconsider the entire rationality of putting wi-fi switches anywhere, let alone in a garage FGS.

 

[scorpiouk]

It's there for a reason.. The garage door opens and IFTT switches the lights on.. I know the automation is not for everyone

 

[flameport]

So I either need to find the Neutral in this lighting circuit

That is the only option.

 

[scorpiouk]

Ok... Thanks.. Been a great help.

 

[ban-all-sheds]

It's there for a reason.. The garage door opens and IFTT switches the lights on.. I know the automation is not for everyone

I think you and those with powers of thinking and awareness will have to differ on what qualifies as "reason".

 

[flameport]

This is the danger that interconnections create:

With no RCD, this would work to power the Wifi thing - power from the light switch returns via the socket circuit:

When someone removes power from the socket circuit nothing happens - until the blue wire is disconnected or cut. It then becomes live because of the connection to the lighting circuit:

Anyone who touches that wire after it is disconnected gets a shock and is injured or dies - even though the socket circuit had no power and tests before disconnecting the blue wire would have shown no voltage there.

 

[JohnW2]

This is the danger that interconnections create: .... With no RCD, this would work to power the Wifi thing - power from the light switch returns via the socket circuit: ...

Indeed - and, just for completeness, it would work to power the Wifi thing (without tripping anything) even with an RCD, if both the circuits concerned were protected by the same RCD.

Kind Regards, John

 

[scorpiouk]

Thanks, both.. It's been removed and I know a bit more..

There are 2 lights in the garage, both on the lighting circuit, with different switches.
So ok to find just one of the neutrals, and use that, just not create interconnects between the different circuits?

 

[JohnW2]

Thanks, both.. It's been removed and I know a bit more.. There are 2 lights in the garage, both on the lighting circuit, with different switches. ... So ok to find just one of the neutrals, and use that, just not create interconnects between the different circuits?

Yep, a neutral from anywhere on the same circuit would be OK - maybe actually from a light, rather than a switch?

Kind Regards, John

 

[scorpiouk]

CU is about 10cm from will trace it back

 

[ericmark]

Not all wifi light switches require a neutral, I used Energenie Mihome which does not need a neutral, the problem is to use IFTTT it needs a hub, you can use up to three remote controls without the hub, but to use smart phones, PC's and tablets to program you need a hub, which means it costs to change make used, this is why I use MiHome stuff, once I had got the TRV's it made sense to get wifi sockets and light switches of the same make.

I will admit I was not totally satisfied, the sockets and light switch have three built in timers, you can select which days of the week they are active for, but I really wanted four timers, I could use IFTTT however if internet goes down that fails.

Also disappointed with geofencing, theory is can set central heating to auto switch on as one gets within a set distance from home, however if the temperature is raised from 16°C to 20°C I found the built in anti hysteresis software resulted in it taking 4 hours, so what I had to do was select 24°C for an hour then down to 20°C to over ride the anti hysteresis software, so had to be simply timed, could not use geofencing, so all this hype about saving money only having the home heated when your on your way home does not in real terms work, unless you manually do it with your phone, which really defeats the whole idea.

Don't get me wrong, the electronic TRV heads, and the wifi sockets did a really good job, the electronic heads controlled room far better than the old wax type, but did not really need to be wifi controlled, and the sockets switched off the extruder alarm just before mothers carers arrived and switched on automatic so could not forget to set, however they were not as good as one sees on the TV.

I use the wifi light switch in the bedroom, saved wiring for two way lighting, however if a bulb blows, or we have the smallest of power cut it auto switches off, I set it to work like an alarm clock and switch on 8 am, however when I removed the timer, a week latter it returned all by its self. Same with sockets, if I programmed it not to switch on every Wednesday some times it got it wrong and switched off on Thursday instead.

 

[EFLImpudence]

CU is about 10cm from will trace it back

That shouldn't take too long.