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Discuss Trying to understand 3-way switch and smart lighting in the Lighting Forum area at ElectrciansForums.co.uk.

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  1. NotALeccy
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    NotALeccy DIY

    Location:
    Staffordshire
    Hello,

    Total newbie here and as you can tell from my name..... I'm definitely not an electrician. I've done a bit of electrical hackery in the past, mostly in cars and a bit of soldering, but this all feels a bit beyond my ability and I'd rather not be electrocuted and die before my 30th birthday. Afterwards..... we can reassess ;)

    Last week, I replaced my bedroom light switch, essentially a standard SPDT light switch with Common Live, Neutral, and Two Switched Live Outputs (L1 and L2), albeit only one was wired up.... with a 21st century equivalent, a 'Smart Wi-Fi switch'. Indeed, I can now turn my lights on from work...... why you'd do that, I'm not sure?

    Anyway, having seen what a trivial task that was, the boss has now decided that we should do the bottom of the stairs too, but that's a whole different gravy train..... for a number of reasons:

    The bottom of the stairs has a faceplate with 3 separate switches.... Switch 1, controls the outside lights. Switch 2, controls the hallway light. Those two are easy, as I'm guessing from a purely electrical basis, the wiring is the same as the bedroom.

    Switch 3....... from what the Internet is telling me, is referred to as a '3-way switch combination' ? So it can be 'live' in either position.

    I vaguely understand the electronics behind this, to a certain degree..... I've not removed the faceplate, but I'm guessing this single SPDT switch will have two wires for the switched lives, one in L1, one in L2.
    When L1 is live, to complete the circuit the upstairs one will have the same combination (or vice versa) and either one can break or make that circuit? Perhaps the dumbest explanation ever, but yeah, it will make sense to someone perhaps.

    That all sounds delightful, but I've looked at the rear of this replacement panel and it's a totally different ball game.

    [​IMG]

    The one above isn't the one I am fitting but is basically the same wiring. We have a neutral far right, common live next, and then we have 3 switched live outputs, L1,L2,L3. I guess the way this device works, is that it's a simple state machine, L is powering the hardware and the software controls which of those are hot and when they are hot, the light will come on.

    By wiring this in, am I going to effectively render the upstairs switch redundant? I assume that the upstairs switch will only work if the downstairs smart switch is permanently on? The same applies to the downstairs switch..... Am I going to be left with a floating live wire? I've read that the easiest solution is to simply rewire the upstairs one to passthrough current at all times and to blank the face off altogether. That doesn't sound clever, or safe to me.

    As you can tell, my knowledge somewhat ends around the time I begin to hypothesise if we can actually fix the issue at hand without killing myself? I've already ordered the 3-way but I can easily use it in the kitchen if this can't be solved. Kitchen is three lovely SPDT's that turn on and off a single set of lights each :) Ahh. Lovely.
     
  2. Vortigern
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    Vortigern Electrician's Arms

    Location:
    England
    Business Name:
    F.H. Electrical
    Remember to take some photos when you try it so we can tell you to get an electrician when you do your next post entitled "Help where do all these wires go", at least it will be cheaper then the electrician doesn't have to trace all the wires you are going to find in there. You sure you have a neutral at the switch? I am curious as to how you got a neutral at the switch in your bedroom.
     
    • Like Like x 2
  3. NotALeccy
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    NotALeccy DIY

    Location:
    Staffordshire
    Love your optimism :D You're almost as optimistic as me!! To be fair, I would always take a photo before disconnecting anything, as I don't want to be in the situation where I cannot revert to my previous position.

    No idea if there's a neutral downstairs. I haven't looked, but I am guessing so.

    The 'neutral' (or is it earth?) was already there in the bedroom. The bedroom light switch was a metal faceplate, 4 wires coming in:

    Red - Live
    Yellow - Switched
    Yellow/Green - Earth? Neutral?
    Blue - ?? (disconnected)

    I removed another faceplate however in a different room, and the wires were:
    Red - Live
    Yellow/Green - Earth
    Black - Switched

    Couldn't see a fourth wire.

    I get the feeling I'm biting off more than I can chew. Might give it a swerve truth be told.

    Regarding a passthrough, the more I think about it, the logical passthrough would be downstairs, rather than upstairs, however the upstairs is a double switch faceplate, not a triple. D'oh.
     
  4. Vortigern
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    Vortigern Electrician's Arms

    Location:
    England
    Business Name:
    F.H. Electrical
    I think this thread will get locked very soon. If you really connected the earth as a neutral to your bedroom switch you are in danger as we speak. I think I will short circuit this and suggest you get an electrician in to do what you want with the lights.
     
    • Agree Agree x 2
  5. NotALeccy
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    NotALeccy DIY

    Location:
    Staffordshire
    OK, you're going to have to forgive me, as I'm not an expert and now I'm slightly worried, so help me out here. If I am understanding your point correctly, what you're suggesting is that the previous switch was also dangerously installed, and that I need to get an electrician in? It's entirely possible that this is the case because the house was renovated before I bought it. Large parts of the electrical system was changed.

    Perhaps I am misunderstanding the the element of danger here as well. I assume if there is danger, then I have energized the ground constantly? So, say a bulb went, then even with the light switched off, the metal ground would still be energized. Am I understanding that correctly?

    I can easily remove the 'smart' switch. It wouldn't take more than a few minutes. However what I'm failing to understand from your point, why/how it is dangerously installed, especially as it is using all the same wiring as was previously there? Or whether it's more dangerous than the previous circuit that was there? If so, I will remove it tonight and we can live without it. I really can't be bothered to get the entire house re-wired just for some convenience.

    As I said, I'll whip the new switch out and have the old one back installed in 15 mins, but just trying to understand where the dangers lie here and what I've done wrong.
     
  6. NotALeccy
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    NotALeccy DIY

    Location:
    Staffordshire
    OK, so from what I'm reading on t'internet, the blue is usually the neutral and this is what should be connected to the neutral (makes sense that :-\). That leaves the question what do I do with the ground? I'm not bridging it, as I'm aware that is called a 'bootleg ground'.
     
  7. Vortigern
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    Vortigern Electrician's Arms

    Location:
    England
    Business Name:
    F.H. Electrical
    I think you need to get an electrician you have opened pandoras box. Although apparently there is hope at the bottom there are a lot of things to get through to the bottom. Anyway your casual description of its earth or neutral suggests you may have mixed them up. You say you took photos of the switch prior to putting on the new one, can we see that? Then we could be more confident in making any statement. The three way switch downstairs is going to be worse. As there will be strapping cables x 2(?) and three twin and earths. Normally, unless recently wired, there is no neutral at the switch, so again I am worried/curious on how you found one at your switch. It is possible but not usually likely. A photo again would help on that one.
    The thing with the downstairs switch apart from the amount of cables is the space available. The switch you are contemplating fitting has a higher profile at the back which will make it even more difficult to fit it in with a switch that will be crammed already and probably they have not thought to put a deeper box in to allow for this.
     
  8. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    I have never fitted one of these but his switch does say neutral (optional)?
     
  9. NotALeccy
    Offline

    NotALeccy DIY

    Location:
    Staffordshire
    Thanks for your help. I genuinely appreciate it. I think I'm going put my foot down on the 3-way and say it's a no-go until I can get a qualified electrician it. I don't do this for a living, it's way over my head. I write software, so I'm essentially playing with fire.... and I'm from Stoke, so we haven't discovered it yet ;)
    This whole thing is clearly way way beyond my knowledge and right now, I'm just keen to get my house safe (again?). Am I right in thinking that if I have connected it to ground, the difference between neutral and ground should be 0, therefore it's not, so I might have energized the entire ground loop on the upstairs lights therefore every ground on that circuit would be live? Permanently? Doesn't sound great.

    I will try and find the photos I took prior to the wire up. Regardless, I will knock off the breaker for the upstairs lights as soon as I get in and remove the Wi-Fi switch, and take some better photos along with how the old one was wired in, which is still sat on my desk. I remember how it was wired in because I knew there was a potential I'd need to go back. It should only takes a few mins to do so. No idea if you'll be online tonight but I'm happy to go without upstairs lights until I get it sorted. Glad I got those bedside lamps now :D

    There is definitely 4 wire cable going in (Red/Yellow/Blue/G+Y). Absolutely positive. So I guess the aim is to identify the blue and G+Y and whether they're ground and neutral or just neutral?

    The problem I had while installing, was when I Googled the colours so I could get a better understanding, there was nothing clearly explaining what each wire colour referred to. I guess it is possible that the previous occupant re-wired with non-standard electrical cable? Like you said, pandoras box.

    I have a feeling when the rewire took place, some efforts was made regarding the hole and 'deepening it'. It is much deeper than previous houses I've been in (indeed I have replaced wall switches before, but not with a smart one) and it also has like a metal cage which I've not seen on other houses before.
     
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  10. NotALeccy
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    NotALeccy DIY

    Location:
    Staffordshire
    Good question regarding whether the neutral is optional. I will read the instructions again tonight. Assuming I wire it without a neutral, I'm guessing it just won't work as it won't be a complete circuit though?
     
  11. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    The red, yellow and blue of that cable are all likely to be live wires as it forms part of the two way lighting. As previously stated it is doubtful the switch has a neutral in place. Best cut your losses and use an electrician.
     
  12. Vortigern
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    Vortigern Electrician's Arms

    Location:
    England
    Business Name:
    F.H. Electrical
    That is the problem with those smart lights they need their own supply so neutral is not optional but required. Which is why the move to putting neutral to switch now.
     
  13. Matthewd29
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    Matthewd29 Regular EF Member

    Location:
    Belfast
    Are you sure that blue is a neutral and it is not a 3core and earth for 2 way or intermediate switching? If there is only 1 blue I would doubt there would be a neutral at an old light switch
     
  14. Matthewd29
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    Matthewd29 Regular EF Member

    Location:
    Belfast
    Sorry I have just realised westward has beat me to it, damn I need to start reading the other comments before writing
     
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  15. Vortigern
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    Vortigern Electrician's Arms

    Location:
    England
    Business Name:
    F.H. Electrical
    And yes you haved apprehended the gist of what I am worrying about making the earth live. But then if you have why did the RCD not trip??? Tell me you have an RCD...Although the 3 core colours you describe are not so much used now so when was the refurb? Do you have certs. for the electrical work?
     
    • Like Like x 1
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