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Lighting question

Former Community Member
Former Community Member
So today I wanted to add another switch in a house.


The extra switch would need to now include an intermediate due to it being already 2wY.


now when I took the switches off, one switch the common has just a single sheath core, the L1 and L2 are a 2 core cable L1 being Red and L2 being black.

This is exactly the same in the other switch.


I thought this must mean there is a JB somewhere ? In the light fitting there is 3 T&E, and 1 single cable which goes into the lamp live! 


I just can’t understand how this could be wired? 


Any ideas?
  • Former Community Member
    0 Former Community Member

    Sparkingchip:

    Is this switching on the stairs?


    When was the house built?


    Is all the lighting circuit wired in insulated singles?


    Are there CPC earth wires at every fitting?


    Do the metal back boxes have nylon fixing lugs to retain the switch plate fixing screws?


    Is there more than one lighting circuit, if do are they RCD protected by more than one RCD?


    Andy Betteridge 



    The switch is for the downstairs hall, currently switched from kitchen and bottom of stairs they want an additional switch at the front door.


    Building is old, don’t know how old.


    No, the house is wired in Red and black twin and earth , the insulated single is only the one fitting I have seen it at.


    The cpc is continuous throughout the property.


    The property is dual rcd with lighting on the same side

     




     

  • 0
    The intermediate switch just goes into the strappers  that go between L1 and L2 of each switch and you can have as many as you want.


    It might be easier to make one of the existing switch points the intermediate and run a three bore and earth out to another two way switch at the new point.


    Andy Betteridge
  • Former Community Member
    0 Former Community Member
    Does this matter which of the 2 switches I choose to make into the intermediate?
  • 0
    5f462969886e826958d65c8e2dada4c5-huge-20200317_205148.jpg

    No, as all the conductors are lives and it doesn't matter which way the current flows.
  • 0
    That will be a lot easier than trying to get into the existing strappers between the boxes.


    Andy Betteridge
  • 0
    I would also check around at other nearby ceiling roses ... it's possible they've nicked the permanent live from another rose that was physically closer, or easier to get to.   The idea of a cable tracker is good. They needn't be expensive. I use one from amazon that's really designed for datacomms work, but on a DEAD mains installation it works fine. And it's cheap enough that if (when) i accidentally connect the tx to something live, it will be cheap enough to replace.


    The only caution is that, as per the covering my posterior side, it MUST be assured the cable is completely dead, as of course being designed for datacomms only it has NO category rating and its behaviour when connected to 230v would be ... undefined but probably messy.


    The same device includes a basic continuity tester which can be handy for when you think you've found the cable you want. Simply flip the switch and short the cable to earth or whatever other wire you were using for the circuit.
  • 0

    Clint:




    Legh Richardson:

    I'm pretty sure there will be a Joint Box (JB) hiding somewhere under the floor or in the walls. We used a 25kHz live tracker on several occasions to chase around the installations to find all the hidden JBs.

    Legh


    What is this 25kHz you speak of? Also how do they work?





    It comes in two parts.

    1. a 25kHz pulsed (the signal is not continuous but pulsing) signal generator that is connected in series with the circuit under test.

    2. A detector, similar to a voltage tracker, that you run across ceilings and walls. The detector will pick up the high frequency pulses to a level of about 600mm of the particluar circuit under test.

    It costed around £200.00. We used it most of the time for tracking rfcs hidden JBs.and buried sockets

    Legh

     

  • 0
    I blew one up ?
  • 0
    Does this device work through masonry to that kind of depth? It seems the 200 pounds or so may be worth it to augment the cheap chinese device i just described that I use frequently
  • 0
    Well, the device we used came from France and worked well through most materials I don't ever remember using it on earthed concrete rebar, although it was very effective. .

    Legh

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