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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
    Just to state older electrics are not what I’m 100% familiar with, I’m use to new builds with everything being at the switch itself
  • 0
    I am not clear how this makes a circuit.


    The two core cable comprises the strappers. One end of the single core goes to L on the load and then to switch one. The other single core goes from switch two to the supply - where is that? Obviously, there is a N to the load, but I am not sure what the "3 T&E" does - presumably it carries N, but what else?


    If you want to put in an intermediate switch, you have to put it in the two core cable somewhere.


    There is no mention of a CPC. Is there one?
  • Former Community Member
    0 Former Community Member
    So you say the L1 and L2 are the strippers?


    An the C from one switch is the switch live of the light?

    The other is permanent live?


    The only thing is I can’t seem to locate where the permanent live is fed? 


    what I meant by 3 T&E, is there is 3 Twin and earth cables up at the light fitting. They all connect into the permanent live and neutrals so I assume they just go off to other fittings.


    How do I introduce an intermediate switch?
  • 0
    IMO, The common of Sw1 goes to permenant live at the JB, the common from sw2 goes to the light switch live, via a JB, the feed to the JB and the neutral/switch line from the JB goes to the lamp.

    You now need to break into the strappers that either run between L1 and L2 of the switches or connect into a JB. It should be reasonably easy if it uses the JB to connect the strappers. You'll need another JB or use a terminal box with at least 8 ways to rewire with two T&Es to the new intermediate Sw and so complete the circuit.

    Legh

  • Former Community Member
    0 Former Community Member
    We speak of the JB but I really don’t know if there is one, I tried doing a brief investigation but couldn’t see one. I will have a bit better look tomorrow.


  • 0

    Clint:

    So you say the L1 and L2 are the strippers?



    You must have the same auto-correct dictionary that I have. ?

    The only thing is I can’t seem to locate where the permanent live is fed? 


    what I meant by 3 T&E, is there is 3 Twin and earth cables up at the light fitting. They all connect into the permanent live and neutrals so I assume they just go off to other fittings.

    So loop in and two loops out? Are you sure that the permanent live to the switch isn't hiding in there somewhere?


    In any event, to make things clearer, the intermediate switch will flip the two strappers. If the cable has any slack, you may get away with one JB, otherwise you will need two. It is just a matter of taking the two strappers down (or up) to the switch and back again. Alternatively, if the cable is accessible, you undo the red/black at one end and bring it down to the new switch. You then insert a new piece of the cable from the new switch to the old one.


    Don't forget your brown sleeving and the new and old colours notice! ?


    And what about that CPC? Clearly there is one in the T&E cables, but from the sound of it, the switches are unearthed.
  • 0
    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
  • Former Community Member
    0 Former Community Member

    Chris Pearson:




    Clint:

    So you say the L1 and L2 are the strippers?



    You must have the same auto-correct dictionary that I have. ?

    The only thing is I can’t seem to locate where the permanent live is fed? 


    what I meant by 3 T&E, is there is 3 Twin and earth cables up at the light fitting. They all connect into the permanent live and neutrals so I assume they just go off to other fittings.

    So loop in and two loops out? Are you sure that the permanent live to the switch isn't hiding in there somewhere?


    In any event, to make things clearer, the intermediate switch will flip the two strappers. If the cable has any slack, you may get away with one JB, otherwise you will need two. It is just a matter of taking the two strappers down (or up) to the switch and back again. Alternatively, if the cable is accessible, you undo the red/black at one end and bring it down to the new switch. You then insert a new piece of the cable from the new switch to the old one.


    Don't forget your brown sleeving and the new and old colours notice! ?


    And what about that CPC? Clearly there is one in the T&E cables, but from the sound of it, the switches are unearthed.



    Lol I didn’t even realise the auto correct ?


    Im pretty sure there wasn’t 2 single core, cables at the light fitting tho, just the one which was connected to the lamp live. 


    Now am I right to believe that one of the switches I will have to have connected L1 and L2 as permanent live and switched live ?

    Apologies if this comes across rookie!


    sleeving is always used by me ? also cpcs were at switches  

     




     

  • Former Community Member
    0 Former Community Member

    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?




     

  • 0
    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

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