The IET is carrying out some important updates between 17-30 April and all of our websites will be view only. For more information, read this Announcement

Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 26 replies
  • Subscribers 31 subscribers
  • Views 7012 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

2 plate lighting question

Former Community Member
Former Community Member
Hi all,


New to the forum so please be kind! I'm starting a rewire of my home and have decided for a multitude of reasons to go with wiring the lighting using the 2 plate method(smart light switches and the like mostly requiring neutral). I was intending and can't see any negatives to doing it slightly differently in that I wasn't going to take the feed for following on differently switched lights from the switch, instead I plan to supply one junction box from the consumer unit and then spur off for each room's lighting (may install a second jb depending on how congested the first is looking). 


In doing this I would avoid there ever being a need for more than 3 cables in a single light switch, i.e. worst case scenario i'd have permanent supply (from jb), switched supply to light fitting and lastly in some cases a 3C & CPC for 2 Way switching. Plus in my mind make future installs easier, i.e. any additional feed coming from one central point.


Can anyone think of any good reason not to do the above? Can't see anything in the regs to suggest this would be a problem? 


Cheers all!
  • 0
    I don't see any regs problem with what you suggest at all.


    If you are going for a central joint box approach, it is more conventional to take everything back there - switch cables and light cables - often with cables with an extra core or two to each position - which then gives you a lot more freedom to adjust layouts at a later date or even make temporary changes (e.g. arrange for a room being redecorated to have its lights switched from another room). Think big adaptable box with loads of wago terminals rather than a traditional round JB with 4 or 6 fixed terminals.


    Central JB approaches also give you some additional flexibility - e.g. the way rooms are divided between circuits - e.g. I have 4 circuits over 4 floors but intermingled so where two rooms meet the rooms are on different circuits (e.g. landing on one circuit, bedrooms off that landing on another) - that way if one circuit fails you should still have some light in every room,


       - Andy.
  • 0
    As above no reason why not, but do be careful with the labelling of the various feeds, and leave plenty of space.

    All the usual concerns about access to the joints for inspection still apply.

    Mike.
  • 0
    But make sure such a central junction box is easily accessible, otherwise you end up with the worst of all worlds.
  • 0
    I think if that's the way you want to do it then go for it.


    The thing is... I wouldn't really class that as a proper '2 plate system' more a 'spiders' set of wiring.


    I know many sparks that cannot wire 2 plate systems, in a conduit setup.


    The thing is, I have never wired a 2 plate system UNLESS, it's in conduit, or maybe... mini trunking.


    Tom
  • 0
    I think that it would be more traditional to have one JB for each lamp-fitting or group of them.


    Remember that either they should be maintenance-free or remain accessible for inspection.


    (I don't call the far end of an unboarded loft space with manky Rockwool accessible.)
  • 0
    I'm baffled to understand why anybody would wire using the 2-plate method unless the support was conduit pipe or trunking.

    However, I've used octopus wiring systems on several ocasions. It works well where you have ground floor rooms or anywhere where there's no space between the floor and ceiling, such as old cottages, kitchens, utility, loo, orangery (that's an upmarket lean to). where there's no loft access or difficult to loop cables above or below the ceilings/floors.

    Unless you make all your JBs accessible then it becomes a pointless activity as far as the regs are concerned.

    Legh
  • 0
    I'm baffled to understand why anybody would wire using the 2-plate method unless the support was conduit pipe or trunking.

    I suspect the OP is using it the literal sense of not needing a third plate (loop terminal) at the light fitting - traditional conduit approach of looping L at the switch and N at the light is usual example of that - but a JB based system sort of fits that definition too (although I can see an equal argument that the JBs introduce extra 'plates' (terminals) so it's not really a 2-plate system after all).


    We've had so many approaches over the years - conduit style (sometimes using sheathed singles), loop at the light, loop at the switch, JB for each light/room, central joint box per floor, systems that are a mix of various of the of the above, the simple 2- or 3-plate descriptions don't really do the job any more.


       - Andy.
  • 0
    Why not just use the traditional three plate system with permanent L, N, and switched L at the ceiling light positions, then just run a three core and earth down to the switches for the N?


    Some advantages.  All terminals are easily accessible for alteration or fault finding.

    A permanent L is available for smoke alarms at the ceiling positions if needed.


    No hidden junction boxes to locate when fault finding.


    I have used a double socket pattress as a junction box with a blanking plate over it as a cover. I have stuffed the many, many  wires into it and produced a really messy result, but it works. A pig to fault find on later or alter though.


    Z.
  • 0
    Why not just use the traditional three plate system with permanent L, N, and switched L at the ceiling light positions, then just run a three core and earth down to the switches for the N?

    'cos you'll have no chance at stuffing that lot into the back one of the fancy decorative light fittings, which seem to think that providing for 1off each L, N and PE is sufficient (some don't even provide a PE terminal, let alone space to add any)?

       - Andy.
  • 0
    I am seriously looking at quinetic gear for lighting rewires now - no switch drops to chase, just a feed to each light via the switched side of the wireless relay.

    The only thing I am still not sure of is being able to provide a dimmer option, although I think I have read somewhere that quinetic do a dimmable wireless combo too, although I have not seen one.

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines