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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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    mapj1:

    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.




    3 core and earth is officially used for two-way lighting but is also used for powering fixed devices, such as extractor fans, that requires both a permanent live and a switched live.


    If 3 core and earth is used with two switches for a light fitting with half light and full light facilities then is there a standardised colour code for the wires that are permanent live, switched live half light, and switched live full light?


     



     

  • 0
    "3 core and earth is officially used for two-way lighting "

    Pardon?
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    Personally I think that brown sleeving with a white stripe should be allowed, and used to indicate a switched live.
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    Re: 'officially used' I read that as 'most commonly used'... and it fits.


    *edit: that being said, anyone finding any random cable, should NOT 'ASSume'. Is that T&E a live feed, is it a switch drop? Is it 12v SELV for a bathroom extractor long since removed?


    Is the 3 core a 2 way lighting circuit? L+N+SL for a fan? Central heating control (maybe converted to 24v and using only the yellow and earth cores? (found that one a few days back).


    To my old and jaundiced eye, there is too much 'caring about what the next sparkie will make of what he or she finds' and not enough 'understand basic electrical principles'. I tend toward the conduit system, even with sheathed cables. Lives loop at the switch, Neutrals at the ceiling rose. And it's a ring main, not an RFC, (that's a rugby football club), voelcb's are fine and get off my lawn!


    [part of that was joking, but seriously, there are as many correct ways of doing it as there are people who can interpret the regs. Just don't be a douche about it, see one of David Savery Electrical's recent videos where someone had swapped the uses of black and grey in a 3 core SWA, halfway down a garden, for no obvious reason]

  • 0

    wallywombat:

    Personally I think that brown sleeving with a white stripe should be allowed, and used to indicate a switched live.




    I cannot argue with that.


    During my training (if I recall correctly, which cannot be assumed ? ) we were told that a short length of brown sleeving as opposed to sleeving a whole length of cable means switched line. That seems reasonable, but on the other hand, take 3 browns in singles for 3 phase (cheaper than buying 3 reels) marked by no, black, and grey sleeves. Must they all be long?


    Short lengths of brown sleeving may easily fall off, which is clearly unsatisfactory. Neither is a wee bit of sticky 20 year old insulating tape (in red).


    So yes, I like the idea of identifying switched line in a special way. 18th+1 DPC?

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    Chris Pearson:


    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!




    The loop-in topology dates from the early 20th century where it competed with (and still competes with) a radial topology. In some buildings a hybrid loop-in and radial topology is used as it best suits the layout of the rooms or if extensions to the original wiring have been added at a later date.


    Most houses wired during the early to mid 20th century used a separate ceiling rose to connect and support the light fitting, and a circular junction box installed in the ceiling cavity for the connection to the wall switch regardless of whether a loop-in or radial topology was used. This schematic continues to be used right up to today with ceiling rose junction boxes and Surewire light and switch junction boxes. The method of bringing neutral wires to the wall switches is a different schematic. Circular junction boxes are still manufactured using a design virtually unchanged since the 1920s (possibly earlier) but no longer meet the wiring regs for installation in difficult to access places or under floorboards.


    The invention of the 3 plate ceiling rose junction box is lost in time but once it became popular it cemented in place the loop-in topology as standard for new builds and rewires as a radial topology was difficult to implement without a separate junction box. I'm unsure whether the inventor of the ceiling rose junction box ever thought that residents may wish to replace them with a fancy light fitting or a decorative ceiling rose in the future leaving them with the challenge of how to replicate the interconnections. I was verbally informed that ceiling rose junction boxes became mass produced in the mid 20th century primarily for use in council housing but (unexpectedly?) became the norm for private housing by the 1970s, although I'm unsure how true this statement is.


    An uncommon arrangement is to have a ceiling rose junction box mounted in a location other than a ceiling. Some houses have ceiling rose junction boxes installed in the ceiling cavity with a length of flex connected to the light fitting or a second ceiling rose mounted on the ceiling. This no longer meets the wiring regs due to screw terminals although it is acceptable for use with a suspended ceiling if the panels can easily be removed in order to access the ceiling rose junction box.


  • 0
    . . .

    Most modern light fittings are designed for a ceiling with just one cable. Rarely is a terminal strip incorporated in order to replicate the terminals in a ceiling rose. Therefore the installer ends up having to use a chocolate block to make the connections. More often than not there is insufficient space in the light fitting to contain the chocolate block so it ends up being shoved into the ceiling cavity with exposed live parts. A very shoddy and potentially dangerous arrangement.


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



     


     




     

    I once got round this problem by retaining the ceiling rose and mounting the fitting underneath it. However this is not going to work for all types of fitting.
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    Alan Capon:

    I agree, looping in to a ceiling rose is by far the most common, and probably the cheapest. I always liked the method in a house I lived in a few years back - two large junction boxes, one for upstairs, one for downstairs. It was easy for decoration, as you could connect two rooms to one lightswitch while you were wall papering. It also gave lots of space for adding additional lights. Its downside was longer cable runs. 


    Regards,

    Alan. 




     

    This method makes a lot of sense for the wiring of newly-built houses. It involves extra cable but is simpler and less laborious - labour expenses are usually greater than material costs. The whole wiring kit can be delivered almost as a "harness" with cables attached, and  the electrician need simply run the cables to the appropriate lighting points or switches before any plaster is applied to the walls. Make the electrical connections later. (Care needs to be taken of course to run each cable to the  right place, or else you end up with switches controlling lights in the wrong rooms - I have known this to happen.) To wire a new house using loop-in could require wiring accessories to be installed before plastering - not the best way round to do things.


    For rewiring of older houses, this method would involve more cabling to be manoeuvred through awkward routes, so the would be little, if any, saving in labour.
  • 0
    The easiest way is to just wire as loop in to a 4 plate ceiling rose with flex and lampholder and inform the owner that if they buy a fancy fitting to ensure that the top bit is a cup that will fit over the backplate (Leave a spare rose backplate for them to lose/ignore when they buy a fitting). Of course you might warn them of a permanent L in the backplate but they often choose to ignore that as well!
  • 0

    ebee:

    The easiest way is to just wire as loop in to a 4 plate ceiling rose with flex and lampholder and inform the owner that if they buy a fancy fitting to ensure that the top bit is a cup that will fit over the backplate (Leave a spare rose backplate for them to lose/ignore when they buy a fitting). Of course you might warn them of a permanent L in the backplate but they often choose to ignore that as well!




    That's fine if your 'new' C18th Venetian chandelier is less than 2kg otherwise you might have to fix a mechanical supporting hook up in place of the ceiling rose. Using the bell cover should be ok to house the connector block. Otherwise you have entered the realm of the over officious ELF.....


    Legh

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