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What is the best way to wire ceiling lights?

Arran Cameron
The ceiling rose junction box with its loop-in wiring is now really showing its age and is no longer a practical (or even safe) installation for most residents who wish to install fancy light fittings. It is still, however, the most common arrangement for new build houses and rewires, probably as the result of the electrician's training and how they consider it to be the norm or they cannot think of (potentially better) alternatives.


So, what is the best way to wire ceiling lights? Should neutral wires be taken to the switches or not?
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    Arran Cameron:




    ebee:

    "There is also the controversy of a permanent live terminal in a ceiling rose."

    What controversy is that then?




    It's not obvious to installers of light fittings, in the same way that a permanent live terminal at a switch is, unless they have knowledge of how loop-in wiring is connected. There have been cases of installers of light fittings receiving electric shocks because the lighting circuit was not switched off at the consumer unit even though it was switched off at the wall switch.




    I don't think that we can expect an ordinary householder to practice safe isolation, but surely sensible people know to switch off at the CU. Or is Darwinian selection in progress once again?

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    So, what is the best way to wire ceiling lights? Should neutral wires be taken to the switches or not?




    See 559.5.1.208. I prefer to loop at the switch personally.

     

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    An unswitched live at the ceiling is sometimes seen in Germany, but it is not because of loop-through wiring, but in case folk want a fan or a heater as well as a light.

    Also sometimes 2 different switched lives, so that you can have all or half lights on  in a complex fitting.

    Neither are as common as just finding a just switched live neutral and earth on their own.

    Pretty much all wiring is loop through switch, mainly as the domestic standard is to have combined lights and power circuits, and you will often see a wall socket and a light switch together by the door, sharing a common 16A feed.  Clearly in such a case you have L+N and E at the socket, so it all continues on as L+ N& E to the light fitting.

    2 & 3 way lighting can quickly become  confusing, and you will often find 2 core plus earth running between the switches, rather than 3+ E as we would.

    So called 'Hamburger' switching exists but is not permitted by current German regs - in this case the lamp is between the sliders of 2 switches, each switched to either L or N (so the lamp is off with either N-N or -L, and on with L-N and N-L. As either side of the lamp could be live it is not considered safe, and should be removed if found.)

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    andydc:






    So, what is the best way to wire ceiling lights? Should neutral wires be taken to the switches or not?




    See 559.5.1.208. I prefer to loop at the switch personally.

     



    I would agree with andydc and 559.5.1.208 where consideration is given to providing a neutral where there is a need to provide power for electronic control.

    Its really a matter of personal choice, convenience, recognised standards and training whether you take the neutrals to the switch. Its based, historically, from the 2-plate conduit wiring system and still is in commercial/industrial lighting circuits where permenant lives are connected at the switches and return neutrals looped in at the light fittings.

    As long as its safe and easily followed by others then it is perfectly acceptable.


    Legh

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    'Hamburger' switching exists but is not permitted by current German regs


    That's a new one on me for LV lighting. Although I'm sure I have come across it in electronic systems in the past.


    Legh
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    Junction boxes with spring clamp terminals are permitted for installation under floorboards as they are deemed to be self tightening and maintenance free.



    There's a little more to the MF requirement than that unfortunately - as well using spring terminals the cables need to be secured (clamped) and usually the terminals de-rated to increase reliability - and to comply with the letter of the regs the whole assembly has to have been marked "MF" by the manufacturer. Just chucking a few Wagos into a Wiska box won't quite cut it.

     

    unless they can easily be removed for inspection



    I'm not sure the regs specify "easily" - just "accessible". I'm still of the opinion that if you get access the position to install the JB and nothing really changes subsequently (like someone tiling it over), then it must still be accessible. Pushed back up through a downlighter hole I think counts as being OK (if not there are lot of Click connectors (e.g. CT101C) that are in trouble).

     

    Light fittings are now designed and manufactured for the global market rather than for the peculiarities of British wiring (which also explains why most recent models are Edison screw rather than bayonet cap) so often only have terminals for one cable rather than three.



    Seemingly, if what I've read elsewhere, the French wiring regs specifically prohibit any sort of looping in at lights (and I suspect sockets too) - and I suspect few other countries have similar. The French seem to prefer chock blocks in round flush boxes high up on walls and branch everything from there - which is all a bit odd really as they tend to use singles in conduit for domestics so could have managed nicely looping N at the light and L at the switch without any extra terminals at all.


      - Andy.
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    mapj1:

    Also sometimes 2 different switched lives, so that you can have all or half lights on  in a complex fitting.




    Do the regs allow the use of a 3 core and earth cable for 2 switched lives or must 2 twin and earth cables be used?




    AJJewsbury:


    There's a little more to the MF requirement than that unfortunately - as well using spring terminals the cables need to be secured (clamped) and usually the terminals de-rated to increase reliability - and to comply with the letter of the regs the whole assembly has to have been marked "MF" by the manufacturer. Just chucking a few Wagos into a Wiska box won't quite cut it.

    Surewire junction boxes are marked MF and they have cable clamps. The manufacturer makes the claim "They aim to be the new standard for wiring a lighting circuit" although I'm not confident that they are a magic bullet solution to the problem (hence the OP) despite using them myself without any problems. They are rated at 16A although most lighting circuits are protected with a 6A breaker.


    Using a Wago shoved into the ceiling cavity above a light fitting to replace the connections from a ceiling rose junction box is probably better than using a chocolate block with screw terminals but it officially won't meet the MF requirement as there are no cable clamps and the wiring is not double insulated.
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    The Wago connectors go in the Wago box and if you are installing down lights the box will normally pass through a light fitting hole in the ceiling.


    Simples, but not as simple as wiring through the switch boxes.


     Andy Betteridge
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    Do the regs allow the use of a 3 core and earth cable for 2 switched lives or must 2 twin and earth cables be used?







    Unless it has changed, and it has been a few years, 1neutral,  2 lives and 1E , so long as both light switches are fed from the same breaker.



    In singles brown, black and oddly purple sometimes used. in terms of cable more like our T and E, you do get "funf-adrig" or 5 core, NYMJ 5-1.5mm , now  in the new 3 phase colours plus neutral and earth.
    scroll to pic half way down


     


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    As others have said, it all depends on the circumstances.


    I rather like a JB approach (nowadays Wago in a Connexbox = MF). If it's in a loft space, then I would say that it is undoubtedly accessible. If it's under floorboards, it starts to get difficult, and all the more so if fitted carpets have been, er, fitted. Under a fashionable tiled bathroom floor is beginning to get difficult (can you gain access to the void without damaging the finish?) and even worse if you have under-floor heating.


    Do it right, do it once is a good principle.


    I think that all of this suggests that looping in at the rose (or hole in the ceiling) is not the best solution. Within a reasonable period, it is likely that a householder will wish to change the lamp-fittings, so make it easy!

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