Electrical advice - how ‘backyard’ is my solution?

[Agent_zed]

The only devices that don’t require touching the circuit are smart bulbs, but the problem with those is that when the switch is off they don’t work. They usually require a permanent live feed and so then the relay would tell a hub to tell the bulbs not to illuminate any more, but they would still be live.

So is the general consensus that I shouldn’t even add a relay to the back box myself?

Forgive my naivety, but where is the danger in that? If all of the terminal’s are connected correctly and there’s no exposed wiring in the back box. What is the potential danger that I’m missing here?

If everything is connected correctly then there isn't any more danger than a qualified person doing the job. There are however 2 potential problems. 1) Knowing you have done it correctly and 2) if something does go wrong then you won't be covered by insurance etc.

I have done the majority of my electrics myself and haven't burnt down my house yet. However there are things I don't know so anything outside of the norm I would look to get advice from a qualified person or get them to do it. Some things you aren't allowed to do e.g bathroom electrics. Kitchens used to be in the same category but that changed I think.

I guess for me the bigger question is why you need so many different methods of turning a light on? I've just got back from a skiing trip and the chalet has pir sensors for the hall way and boot room and that was really useful. That is a simple install. Do you really need to turn it on with your phone? It probably seems cool for a while until you realise you have to unlock your phone each time and find the app, whereas you can just walk into the room and have the pir turn it on.

In my house I also have a completely separate 12v system that runs off a 12v battery in the garage. I have some undershelf lights and a couple of runs of led lighting. The pantry light is on a 12v pir and the roof light is on a remote control (I can change the brightness level which is great for early mornings when I don't want full lighting). Works well for me and in case of a powercut I have lights. I have 1amp fuses on the cables so they can't short and burn my house down that easily. I charge it when the sun is shining and I'm making electric, so they don't cost me anything to run.

 

[MarkAW]

Very sound advice & guidance.
I know it can be difficult to accept what we are being told sometimes, but the people
offering it have no other agenda, other than you and your family's safety and well being.

I said that last one, not chief sawdust maker

 

[Luckosaurous]

If everything is connected correctly then there isn't any more danger than a qualified person doing the job. There are however 2 potential problems. 1) Knowing you have done it correctly and 2) if something does go wrong then you won't be covered by insurance etc.

I have done the majority of my electrics myself and haven't burnt down my house yet. However there are things I don't know so anything outside of the norm I would look to get advice from a qualified person or get them to do it. Some things you aren't allowed to do e.g bathroom electrics. Kitchens used to be in the same category but that changed I think.

I guess for me the bigger question is why you need so many different methods of turning a light on? I've just got back from a skiing trip and the chalet has pir sensors for the hall way and boot room and that was really useful. That is a simple install. Do you really need to turn it on with your phone? It probably seems cool for a while until you realise you have to unlock your phone each time and find the app, whereas you can just walk into the room and have the pir turn it on.

In my house I also have a completely separate 12v system that runs off a 12v battery in the garage. I have some undershelf lights and a couple of runs of led lighting. The pantry light is on a 12v pir and the roof light is on a remote control (I can change the brightness level which is great for early mornings when I don't want full lighting). Works well for me and in case of a powercut I have lights. I have 1amp fuses on the cables so they can't short and burn my house down that easily. I charge it when the sun is shining and I'm making electric, so they don't cost me anything to run.

The phone was just an example. It will all be ran through a central smart home hub. The presence sensor will only turn the light on when the luminance of the room is beneath a certain value, and it would also trigger the blinds to close when the light is turned on.

I want the functionality of the light switch to remain normal, but to have the light switch to trigger these different automations. It also adds voice control by pairing it with Alexa or Siri through my watch.

The reason for the smart relay is so that the smart home doesn’t become dumb as soon as a visiting friend or relative turns the light switch off.

Absolutely nothing about this needs to be done, I’m just being a nerd, but it will make my house more enjoyable to me.

 

[LancsRick]

Whilst there a few different bits of advice given in this thread which I know contributers will have different opinions on I think you're getting a clear message here - don't mess unless you know what you're doing.

As had been said, if it's lightweight block then you can just scrape the recess deeper, it's very soft. I suggest anything else you get a qualified sparky in based on this discussion. I'm not saying that to be dismissive, just that it's not worth doing wrong.

 

[Luckosaurous]

Whilst there a few different bits of advice given in this thread which I know contributers will have different opinions on I think you're getting a clear message here - don't mess unless you know what you're doing.

As had been said, if it's lightweight block then you can just scrape the recess deeper, it's very soft. I suggest anything else you get a qualified sparky in based on this discussion. I'm not saying that to be dismissive, just that it's not worth doing wrong.

Agreed. I was hoping someone would make me aware of a magic wand solution that would be less messy.

I’m just a bit confused why people think that adding the relay into the backbox at of the wall switch would be dangerous? I’ll be using the correct gauge of wire, all terminated so that no copper is exposed. What am I missing? Is there a danger here that I don’t know about, or are people just so shocked by my initial wild suggestion that they think I will probably try using blu-tac to join the circuit?

 

[Agent_zed]

Is there a danger here that I don’t know about, or are people just so shocked by my initial wild suggestion that they think I will probably try using blu-tac to join the circuit?

I think it was your original post about running cables from other circuits etc that perhaps made people question your safety/knowledge.

If you follow all of the correct rules and regs then it should be fine. The problem comes if you were to have random cables from other circuits run in non-standard locations that are plonked on top of kitchen cabinets etc. Just do everything by the book and there is no reason it should be dangerous then.

 

[Spectric]

If you are only replacing a light switch using only the wires currently there with a so called smart switch then you are not modifying the original design intent so there should not be any issues. What you must be aware of is that if using a metal switch plate, ie conductive then that MUST be earthed to the CPC directly, you cannot rely on the backbox being earthed and the faceplate earthed via the screws so a link will be needed.

 

[Sideways]

I’ll be using the correct gauge of wire

How will you know what is the correct gauge of wire ? You don't know the rules about how to calculate that or how to install it.
Your electrician needs to be familiar with a 500 odd page book of rules so they can apply the overarching principles plus the 1 or 2% of specifics to any job. They need a copy of the book to refer to as no one can memorise everything and enough knowledge to apply what they read. They need other education, training and experience, plus tools. Yet you seem to think a few pieces of advice from total strangers on the internet is an adequate substitute.

Don't be offended but this isn't youtube full of idiots who don't know what they are doing but are happy to encourage others to copy for the sake of their own ego and pocket. The fact that people aren't stepping up to give you a "magic wand" should be taken as a hint.

Interestingly a year or more back we had a thread that this reminds me of. Someone asking electrical questions but determined to ignore any advice that didn't fit with their view of the world. I learnt a new term from that thread. The Dunning- Kruger effect.
https://en.wikipedia.org/wiki/Dunning–Kruger_effect
With your best interests at heart ....

 

[Luckosaurous]

How will you know what is the correct gauge of wire ? You don't know the rules about how to calculate that or how to install it.
Your electrician needs to be familiar with a 500 odd page book of rules so they can apply the overarching principles plus the 1 or 2% of specifics to any job. They need a copy of the book to refer to as no one can memorise everything and enough knowledge to apply what they read. They need other education, training and experience, plus tools. Yet you seem to think a few pieces of advice from total strangers on the internet is an adequate substitute.

Don't be offended but this isn't youtube full of idiots who don't know what they are doing but are happy to encourage others to copy for the sake of their own ego and pocket. The fact that people aren't stepping up to give you a "magic wand" should be taken as a hint.

Interestingly a year or more back we had a thread that this reminds me of. Someone asking electrical questions but determined to ignore any advice that didn't fit with their view of the world. I learnt a new term from that thread. The Dunning- Kruger effect.
https://en.wikipedia.org/wiki/Dunning–Kruger_effect
With your best interests at heart ....

It’s a 6 amp lighting circuit so 1mm should be fine but if I wanted to be certain then 1.5mm should be more that enough. Unless I’ve misunderstood then I only need to make sure the cable is capable of taking a higher load than the breaker?

I would be installing the relay to act as the switch, meaning no cabling is added to the lighting circuit. The relay would then send a live to the switch and back so that it can detect if the switch is open or closed. At most this would probably equate to an extra 100mm of cable. Provided the cable is rated to take that load then I don’t see the problem.

Again, I’m willing to be educated if I’m wrong.

Edit: diagram below

 

[Sideways]

Yet you seem to think a few pieces of advice from total strangers on the internet is an adequate substitute.

Hint isn't going in .....