"best" way of wiring lighting circuits? Complete re-wire

I fear I'm over thinking it, but any way of wiring a lighting circuit seems to come with disadvantages...
1. standard UK loop-in power at each light fitting advantages: standard, have unswitched power available at fitting for future e.g. ceiling fan/light etc disadvantages: many modern light fittings don't have enough terminals, or much space to add them
2. loop-in power at each switch advantages: single wire to each light fitting, have unswitched power available at fitting for future e.g. timer, neon etc disadvantages: lots of wires to each switch, need extra terminals behind each switch (question: can I use the "unused" terminal of a 2-way switch to join the neutrals, so that when the switch is "off" the two wires going to the light fitting are shorted?)
3. junction boxes in the ceiling advantages: single wire to each light fitting and each switch disadvantages: junction boxes are supposed to be accessible, but most won't be in practice. won't have unswitched power anywhere except junction box
4. wire singles: neutral looped into fittings, live looped into switches advantages: saves copper! fewer wires in general disadvantages: induction loop interference, can you still buy cheap singles, won't have unswitched power anywhere
5. any other options?
6. mix and match the above as convenient advantages: ? disadvantages: confusing. will probably end up without unswitched power where I need it!
I know in the past I lived in a house with standard loop-in wiring to each light fitting, and had to put junction boxes in the ceiling to nicely accommodate several new light fittings with only LNE terminals.
Thoughts?
Cheers, David.
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wrote:

Fan feed is a fairly big point imho, I'd look to include unswitched live at the ceiling lighting points whatever scheme is used.

If you did it would suffer one of the 2 downsides of the Carter system, which was outlawed in the 1930s. Ie that a switch failure is liable to short out the supply, its a fire risk.

With a tool they could be, ie by unscrewing the light fitting first. Also one can solder inside the jbox, fit the wires in the screw connectors as normal, but leaving long tails, and solder those. The screw cons then provide mechanical restraint for the solder joints.

you can have it anywhere you want by using an extra cable core.

again you get L, swL and N anywhere you want by fitting the necessary singles to provide it.

well, yes :) ... I doubt its what you'd want though.

NT
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Couple more options:
Mains to the light fittings, with the cable to lightswitch being cat5, run on 12v with a relay - you can then use anything at all for the switches, which much opens up the decorative possibilities - you can also add no end of extra switch ways later if desired
A ring circuit for lighting gives increased safety and reliability.
Its sometimes worth adding extra cable cores, so that later there is the option to add a greater number of switch ways, enabling easy switching between differing lighting levels.
NT
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When I rewired a house for home automation, I ran all the switch and lighting point wires back to central connection points (actually consumer unit shells, because the DIN rail made it easy to mount X10 dimmers and relays). It's easy to change the way things are switched, rather like a Cat5 wiring closet, and (important point for selling) it's easy to strip out the home automation control and revert to manual operation.
All switch drop cables are triple and earth, which allows either to get a neutral to the switch or to add a second switch in the future. Again, many of the lighting points are triple and earth, for future flexibility.
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Andrew Gabriel
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Cool!
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On 02/06/2010 11:11, Andrew Gabriel wrote:

How would you handle multiway switching in such a scheme?
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On 02/06/10 12:26, Jim wrote:

Multiple X10 senders (switch) for one address (light)?
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Tim Watts

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With home automation, all the switches are momentary action anyway, so I simply wire multiple switches to one of the computer inputs.
If I strip out the home automation, I can fit impulse relays in the consumer unit shell and continue to drive with the existing momentary action switches.
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Andrew Gabriel
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Yup. Very useful if you decide to add table lights etc switched from the same place at a later date.
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*Who are these kids and why are they calling me Mom?

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On 02/06/10 10:36, David Robinson wrote:

Agreed - don't like this as it bones you if SWMBO gets one of those Ikea fittings with sod all space for terminals.
Pity they don't do a flush ceiling rose but you could DIY one with a round dry lining box and terminal strip...

No! There's no guarantee that the switch is break-before-make (unless it says so) which would result in a rather noticeable bang followed by no lights.

Hager-Ashley maintenance free JBs with spring terminals. The jury is still out on their longevity but the regs allow these, because the manufacturer rates them as fit for purpose. But I personally wouldn't stick then under tiles or laminate just in case! Under floorboards is fine, and under easily liftable floorboards, you could use a screwed JB anyway.

And you'd need either full *continuous*[1] conduit/trunking or double insulated singles. Unenclosed single-insulated singles (wibble) are NOT allowed anywhere.
[1] That means continuous, no 1" gap by the light because it was too hard...

JBs in a more remote but accessible location? Eg group them in a few locations and have little access panels in the floor. More cable required, but easier to maintain.
As all my lighting is run mostly on one level, with a dormer conversion, I've made up 4 large junction boxes with DIN rain and DIN terminals. One in each quadrant of the house, in the corner voids behind the dormer room walls (where there are large accessible voids).
Not for everyone - costs more (could have used lots of regular JBs for the same effect, but I want somewhere to stick relays for a bit of remote control) and needs more cable. However, not *that* much more in my case due to the layout.

Another option - permanant power to all lights and fit radio controlled units to each one. No cables to the switches. Cool, but costs a fortune. getting more popular though - check out Homebase and B&Q - they seem to be increasing the range of these units.

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Tim Watts

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Thanks for all the answers...

Special thanks to you Tim and also to NT for pointing out problems with this!

Fine upstairs (JBs grouped in loft) but _really_ painful for downstairs lights.
Downstairs I think I'll just loop into switches, join neutrals using a chocolate block (one bit of!), and go from switch to fitting with 3- core + earth to allow me to send unswitched live to fitting later if I need to.
Shall I leave the initially unused strand of 3-core "floating" (I'm worried about it touching something live and causing problems), or parallel it to the switched live both ends, or wire it into the earth both ends to keep it out of harm's way?
Cheers, David.
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wrote:

I usually earth spare cores.
Adam
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wrote:

I usually leave spare cores unstripped and put tape over each end, so it looks spare, and not a possible replacement to a broken earth.
Toby...
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wrote:

Hang on a second - with standard 3-core + earth (brown, black, grey), I don't have a blue for neutral.
I'm sure I've used 3-core before with one of those colours carrying neutral (interlinked smoke alarms being the most obvious; brown live, black = neutral, grey - interlink I think) - but where in the regs does it say that this is allowed?
Specifically, the on-site guide says neutral = blue, and that's it.
Brown obviously works for live, and black and grey obviously work for switched live - but black or grey for neutral - where does it say I can do that?!
Cheers, David.
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wrote:

You need some blue sleeving.
Good practice is to sleeve the grey not the black with blue sleeving and use that as the neutral connection where needed.
Adam
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wrote:

OK - will just swapping the last 1-2cm of the insulation for blue insulation (stripped from a blue wire elsewhere) do? That's what I've done in the past to mark the blue as brown in a switch feed (but back then, no one was checking!).

Why grey not black? (Just interested).
I was going to use brown for the switched live - but then thought "if/ when I want both switched and unswitched live down this cable, brown will definately be unswitched live, so grey (or following your advice, black) will be switched".
Pity there's no proper guide on the use of 3-core colours in various scenarios, including this one. Am I correct in believing this means it doesn't actually matter?
Cheers, David.
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On 02/06/10 21:11, David Robinson wrote:

Heavens no. You'll have a broken point in the insulation. You can use blue insulating tape (B&Q) instead of sleeve.

Trying to break the association that black is neutral - or that's the story I heard.

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Tim Watts

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Good point. Though it was more like 0.5cm, so was almost in the switch terminal anyway. I don't like insulation tape, but I agree it's safer in this context.

Interesting. That's quite funny really - in the old colours, I used the Blue of 3-core for the Neutral on the smoke alarms precisely because it was neutral in the "other"(at the time, flex only) colours.
(I hate these new colours - but I know I'm 5 years too late to say it!)
Neutral Grey it is then.
Thanks for all your help.
Cheers, David.
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In article

But the three phase colours predated the change in flex colours by many many years.

It should have been done years ago when the flex colours changed - you'd have been used to it by now. ;-)

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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Nah - they'd still be lousy colours for being able to tell apart in the dirt/dust/dark! ;)
Cheers, David.
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