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As to dangerous, unknown, not enough info/pics. It just worried me for a moment when you mentioned neutral/earth somewhat nonchalantly. But it sounds like it is not a neutral anyway.
 
Not only am I dumb. I'm really really dumb. Having actually looked a bit more carefully, I can see that I'm energizing the earth :( The green and yellow is earthing on the metal frame of the holder. I can't believe I've made such a dangerous mistake. Thank you for highlighting this to me.

Here are the photos anyway, the question is, is it safe for me to reinstall the old switch and what does the blue wire do? Any help at this point would be absolutely wonderful.

Is it worth me disconnecting the earth to see if it works? On a purely academic level?

Trying to understand 3-way switch and smart lighting 20171113_183053 - EletriciansForums.net

Trying to understand 3-way switch and smart lighting 20171113_183030 - EletriciansForums.net

Trying to understand 3-way switch and smart lighting 20171113_183002 - EletriciansForums.net

Trying to understand 3-way switch and smart lighting 20171113_182951 - EletriciansForums.net

Trying to understand 3-way switch and smart lighting 20171113_182620 - EletriciansForums.net
 
The reason it functions is because you have connected earth to the neutral terminal and I am guessing unlike you other switch this one needs a neutral to function which the earth will do however, that is not the way to go about it and you need to reinstate the original switch. I doubt the unused blue is a neutral, put the original one back but if in doubt get an electrician in to check it.
 
Ditch the not so smart switch and reconnect the original as your bottom picture shows.
 
Oh for sure, it's coming out. I am happy to admit defeat on this one. I definitely need to get a pro in when doing this stuff in the future. I will get a qualified electrician in, probably after Xmas now to install it, if I decide to install it at all. It might not be worth the effort and nothing is more important than safety when it comes to your house, especially not for a bit of convenience!!!

Just while we're on the subject, how much would/should a good electrician charge to install a neutral cable? Is it a rip-the-wall out job? If so, I think I'll give it a swerve :)
 
It may be possible to re wire the circuit to provide neutral down the existing cable but that would have to be investigated.

Also, I think you are confusing Neutral,l and Earth of a 230v A.C. system with 0v/ground in electronics. In an A.C. system, earth is connected to the Neutral at the supply end and to the general mass off earth, but from that point on it is only used as a safety system to make sure that all exposed metal work remains at 0v to earth. The Neutral cable provides a return path for all connected loads. Lighting circuits are often wired with a live and neutral in the light fitting and then a pefmenant live wire is run from the fitting to switch with a switched live running back to control the light.

As mentioned it is possible to get smart switches that don't require a neutral (these work by sitting in series with the load (bulb) and passing a small current through it even when off.

There are also smart dimmers that can be wired in at the light fitting, using the existing switch as a control input.

But as already stated, it would be best for you to find an electrician who is experienced in wiring these smart switches. If you find the right solution it may only involve a couple of hours of labour to get a few circuits wired up to smart switches. All tested and certificates issued.
 
What worries me, having established the earth is energised (possibly) is why did the RCD not trip. I applaud @NotALeccy your honesty in checking and listening and "owning" up to what is a very understandable mistake in the circumstances. Can you put up a picture of the box which controls this circuit so we could see if you do have an RCD.
 
The N connector in the switch is only for the switch electronics, which probably only draws a couple of w so may not be enough current to trip the RCD
 
True there may not be enough current doing the maths, but it is something I would be inclined to test while I was there, I mean RCD tests to make sure everything is ok with the RCD.
 
Thanks for the replies everyone. I've reverted back to the old flick switch. Boss isn't happy, but then again I'd rather live than be electrocuted while changing a bulb.

@shaun1, indeed my knowledge of AC is really tiny, as you can tell. The kind of electronics I've done is mostly automotive, where it's a case of live/ground, done.... Much easier than this

I'll get a photo of the 'RCD' or breaker box or whatever it's called :)
 
They do not have rcd protection and that Protek device should not be fitted to that board it is not compatible.
 
Are you saying its unsafe then? Shouldn't this have been spotted on the £700 home buyer survey, bearing in mind I had the full building survey? Just wondering if this is normal on a house or have I been stitched up a bit?
 
Am i the only one wondering if the"boss" is actually the OP's life-partner,or a work place senior figure,unusually interested in bedroom lighting operation? ;)
 
Can anyone explain how light can be on and no hot terminals on one of the two witches detected by the warning voltage? I guess this is a big clue as to how to convert my wired.

Look for suitable equipment to check hot wire.
@thuyln2 - Hi, just to explain the forum is based around the UK standards and practices and these may differ from that of Vietnam and any advice given may not reflect your local practices and regulations, please factor this into any advice you take.
 
Are you saying its unsafe then?

Your installation is not unsafe (subject to EICR!). The sticker on your consumer unit (the photo of switches etc.) says it's due to be inspected last year. So an EICR is due for your installation. There is no RCD protection for your lighting circuits, hence there would be no tripping with the way you have wired your light switch.

If you look at the switches you have a mixture of different brands. Schneider took over Square D, and now if you want to replace those switches you use a Schneider. The protek as @westward10 said, is not compatible with the consumer unit. Although of all alternatives protek would not be my choice as I think they are not good quality. Should be Schneider.

As for the survey, unless you had paid an electrician to do an EICR you would not really know what the state of the electrics were/are.
I would not beleive a surveyor who told me the electrics are fine in any event. That would be like asking Jamie Oliver if your car is OK. I think if you check the weaselly words used in such a survey you will find that there are disclaimers which tell you; We took your money and told you what we think but don't rely on it, if you do we will insist it's your fault not ours, and if you have enough money to pursue it we are in trouble.
 
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Your installation is not unsafe (subject to EICR!). The sticker on your consumer unit (the photo of switches etc.) says it's due to be inspected last year. So an EICR is due for your installation. There is no RCD protection for your lighting circuits, hence there would be no tripping with the way you have wired your light switch.

If you look at the switches you have a mixture of different brands. Schneider took over Square D, and now if you want to replace those switches you use a Schneider. The protek as @westward10 said, is not compatible with the consumer unit. Although of all alternatives protek would not be my choice as I think they are not good quality. Should be Schneider.

As for the survey, unless you had paid an electrician to do an EICR you would not really know what the state of the electrics were/are.
I would not beleive a surveyor who told me the electrics are fine in any event. That would be like asking Jamie Oliver if your car is OK. I think if you check the weaselly words used in such a survey you will find that there are disclaimers which tell you; We took your money and told you what we think but don't rely on it, if you do we will insist it's your fault not ours, and if you have enough money to pursue it we are in trouble.
Indeed.... about a month before we bought the house as well. I should have asked the seller to get this sorted for me, I might have had a solid case to demand it. I never spotted it though. Unless you know what you're looking for, you really don't have a clue.... and I don't. They weren't the best seller in the world though, I won't lie. They would have probably told me to do one.

Is it worth replacing those switches (not me.... obviously) with modern day Schneider's then? Would this bring it up to 'modern standards' or does it need an RCD too? How much we looking to bring my house up to a safer spec? I do feel a tad duped, as I suppose the previous seller should have done it, but if you're selling a house, you're going to avoid doing any work at all, if possible. Can't blame them.

With regards to the dumb 'smart' switch. I've had a word with the electrician at work who does all the office wiring and he's going to have a look for me at lunch to see if it can be safely installed. He's installed a few in the office already. He's said, if I have described it properly (which I probably haven't), the 3rd core (blue?) is probably going up to a junction box in the loft area but will disconnected. He said that can be connected to the neutral in the light fitting and that provides a safe neutral. I have a feeling that is what @shaun1 described earlier. If that's not the case, then the simplest way is to attach a new wire to the old one and run it up the wall, assuming it's not secured? I think I get what he is saying.....

He also said the downstairs one could be an absolute nightmare, involving floorboards coming up. That won't be happening. I'll send it back.

Thanks everyone for your help on this, and I'm very glad that my house is a bit safer now. As for these smart switches, I think I'll recommend giving them a swerve going forward. Do modern houses have neutrals in the wall wiring yet?
 

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