Converting 2 wire light switches to 3 wire (i.e. adding neutral)

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rapidnailer07
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Converting 2 wire light switches to 3 wire (i.e. adding neutral)

Post by rapidnailer07 »

All the switches in my house are traditional 2 wire light switches (i.e. no neutral). Most of the switches are classic rotary knob dimmable ones, some are just the simple mechanical on/off. Some of the lights are controlled 2 way so there is a rotary dimmable switch with a push on/off at one end and a standard on/off switch at the other. All the bulbs are dimmable LED and vast majority of the bulbs are ceiling mounted spotlights.

I would like to upgrade to a smart lighting solution. Due to the vast number of spotlights, it is too cost prohibitive to go with a smart bulb solution like Philips Hue and thus I am thinking of wifi connected smart switches. As I understand, there are smart light switches that work off light switch that doesn't have neutral and there are ones that require neutral. From what I understand, the non-neutral version work by still sending a small amount of power to the bulb (not enough to turn it on) which in turn feeds the switch the power so that it can keep itself active. Where as the neutral version can fully shut off the bulb while still keeping power to the switch. The non-neutral version will thus have a constant vampire drain and this will use more power.

My question is, what kind of cost am I looking at to re-wire the light switches and bulbs so I have a neutral at the switch? What will the work involve? Will my entire ceiling have to come out to give access to the lighting wires? Or is it something that can easily be added without too much disruption?

I don't know how much vampire drain there will be, but I feel it will add up over the years especially given how many light switches and bulbs I have.

Thoughts/suggestions?
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Someone-Else
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Converting 2 wire light switches to 3 wire (i.e. adding neutral)

Post by Someone-Else »

The theory of what you want to do is easy, run a 3 core and earth from each ceiling rose to each switch, connect the Live and switched live and earth as they are now, then connect the neutral, change the switch job done.

As for how much, that would depend on what is involved. Yes furniture would have to be moved, carpets lifted, floor boards lifted, walls chased out, plastering, redecoration (To cover the new plaster)

It's a novel idea to have "smart lighting" I have some, but I also have a couple of Hue lamps (They still draw current when off, and are connected to the hue bridge, so even they use a tiny amount of current) But the one smart lamp I use the most is.................sitting in a "portable" bed side lamp, plugged into a normal wall socket. I do have a couple of RGB "smart lights" never use them.

I have even seen RGB lamps in ceiling lights in disco mode, it looked silly, but I really didn't see the point.

I really think all these smart devices are clever, but of no real benefit.

But if you want to do it, it's not my money. If you still want it done, you may as well have a complete re wire. Subject to do you really need it.
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Converting 2 wire light switches to 3 wire (i.e. adding neutral)

Post by rapidnailer07 »

Great thank you. Another question just to help me understand. Can normal non-smart switches (i.e. simple on/off and rotary dimmable switches) be used with neutral switched lights? Still within the non-smart world, what about where you have 2 way switching (i.e. one bulb with two switches controlling it). If the switch lighting has neutral wiring, can these still work?

Essentially, is the neutral wired switches backwards compatible with all the different traditional light switches?
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Converting 2 wire light switches to 3 wire (i.e. adding neutral)

Post by Someone-Else »

You are confusing yourself, but I think I see why.

First of all (For clarity) You never switch a neutral on its own, as that means the item in question is still live.
Some items (and some sockets) do have "double pole" switches, these switch Live AND Neutral. (So they switch both, not just the live)

Back to the light switches.
If for the sake of argument, you had a 3 core and earth run to each of several switches, the extra core being to supply a neutral for a smart switch, and you changed your mind and want a normal on off switch, it would not be a problem as you would swap the switch and just not connect the neutral, though the neutral would have to be isolated (Wago or choc bloc)
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Would you hit a nail with a shoe because you don't have a hammer? of course not, then why work on anything electrical without a means of testing Click Here to buy a "tester" just because it works, does NOT mean it is safe.

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rapidnailer07
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Converting 2 wire light switches to 3 wire (i.e. adding neutral)

Post by rapidnailer07 »

someone-else wrote: Wed Sep 16, 2020 12:41 pm Back to the light switches.
If for the sake of argument, you had a 3 core and earth run to each of several switches, the extra core being to supply a neutral for a smart switch, and you changed your mind and want a normal on off switch, it would not be a problem as you would swap the switch and just not connect the neutral, though the neutral would have to be isolated (Wago or choc bloc)
Yes, this is what I meant. Just wanted to confirm that having a neutral wired light switch doesn't prevent me from moving back to old fashioned switch. But sounds like you're saying it won't. Thank you.
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Converting 2 wire light switches to 3 wire (i.e. adding neutral)

Post by ericmark »

An electronic switch needs power, be it through the bulb or line to neutral does not matter it still needs power to work. With the type with a neutral we have no idea how much power it is using to work it, but with the type which has no neutral we know the power used is very low as otherwise the bulb would light.

There as you say has to be a current through the switch and much is down to the bulb used. With BA22d bulbs I have had no problems, same with E14 (SES) some GU10 have been OK but one or two have had problems, and G9 bulbs have required a load capacitor.

But even with a simple on/off switch there are losses, with DC it would switch on/off no leakage, but we use AC and there is always some capacitive and inductive leaking, we are getting into the theory of radio waves, and matched feeders etc, I am told in Africa the distances involved they have had problems with power disappearing due to using AC, but with a small island like the UK the distances are not a problem. However when we first went from tungsten to fluorescent bulbs we starting getting problems with them flashing specially with two way lights where the switch cables are longer.

So every bulb is designed to allow a small amount of current to flow without lighting it, an LED will give between 100 to 120 lumen per watt, and with a large package like the replacements for a fluorescent tube they are not much below 100 lumen per watt, so a 24 watt tube will often be around 2400 lumen, but as you go smaller so the lumen per watt goes down so a 6 watt bulb is around 500 lumen, unless you go for a DC bulb, the specials for boats and caravans as in the main 100 lumen per watt or better even when small, a 2.4 watt G9 is 230 lumen, but a 2.5 watt AC bulb is 200 lumen.

So larger bulbs like this 13.5 watt can exceed the 100 lumen per watt at 1600 lumen so to save energy don't use MR16 type bulbs, OK I do use them as they do what I want, but my old house had a 58 watt fluorescent tube in the kitchen, and my son changed this for a set of GU10 bulbs and the watts and lumen output are nearly identical, they cost a lot more to replace and with a HF ballast on the fluorescent there life is nearly the same too, so £2 for new fluorescent tube or £20 for 9 GU10 bulbs so only gain is it looks better, and switches on faster.

Personally I would prefer a light switch with a neutral, if there is a neutral available, but as far as power use is concerned it does not matter, as far as allowing any type of bulb yes those with neutral work better, but there is no power saving. With a boat or a caravan the owner is very aware of how much power is being used, as they need to recharge the battery so bulbs like these 10 - 30 volt DC golfball bulb 2.6 watt 286 or 314 lumen depending on colour temperature are popular, but hardly worth rewiring a house to use battery powered lighting. And if worried about power used then forget dimming bulbs.
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