3rd Amendment Tails Entry

Discussion in 'Electricians' Talk' started by DanielQ, Oct 8, 2018.

  1. DanielQ

    DanielQ Member

    I have too many lights circuits, just downstairs and garden around 13.

    I bought this Wylex CU because it was the only 10 MCB one that I could fit in between the wall studs.

    After your comment I think I would be better splitting the lights upstairs and downstairs to different MCBs.

    In your opinion is there anything wrong with wiring this way to a central junction box?
     
  2. Risteard

    Risteard Screwfix Select

    @Coloumb is not an Electrician...
     
    Magicspark and DanielQ like this.
  3. Coloumb

    Coloumb Screwfix Select

    So long as you have designed the loading and sized your cables correctly then it should work. As said, just very hard to document. Might have been better to use a system like the sure wire distribution box.

    You should have come on here sooner and asked about what you want to do tbh.
     
    DanielQ likes this.
  4. DanielQ

    DanielQ Member

    What Coloumb says makes completely sense and It seems to know what he is talking.

    Could you please share what you think about a centralised junction box for the lights like the one I am installing? Coming from an electrician it would be very interesting to know.
     
  5. DanielQ

    DanielQ Member

    Yes, all the cables for lights and switches are 1.5mm and all the lights will be LEDs, so confident with this.
     
  6. Coloumb

    Coloumb Screwfix Select

    Also I take it these ARE ALL radial ctts, your not feeding ring finals from your JB.

    I don't work as a spark any more, mainly DIY. It's no big secret so not sure why anyone's getting busted up over it.
     
  7. DanielQ

    DanielQ Member

    No rings for the lights.

    MCB 1- Will supply to the biggest JB downstairs and a small junction box in the bathroom.

    MCB 2 - Will supply to the junction box in the loft.

    Each junction box is in "Hub and Spoke" for all the fitting and lights on the floor.
     
  8. Coloumb

    Coloumb Screwfix Select

    And for the socket ctt's?
     
  9. DanielQ

    DanielQ Member


    I have 3 separate rings. Kitchen, Gnd and first floor. Each appliance with a fused switch ran from a different socket.

    Oven and hob are connected to a separate MCB and each of them with separate fused switch.
     
  10. retiredsparks

    retiredsparks Super Member

    Daniel, Is this an elaborate windup ?
    I certainly hope so.
    Rs
     
  11. DanielQ

    DanielQ Member

    What do you mean? I don't get you.
     
  12. Bob Rathbone

    Bob Rathbone Screwfix Select

    if you intend to use separate holes you must make a saw cut between them. For eddy currents issues, this joins the holes and makes them one so that eddy currents do not circulate. Any bushes used must be non metallic.
     
  13. Risteard

    Risteard Screwfix Select

    Not non-metallic but non-ferrous.
     
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  14. Bob Rathbone

    Bob Rathbone Screwfix Select

    Any case of the CCU that is a metal, such as aluminium, will suffer the issues of induced EMF's if separate holes are used without a slot. Consider a transformer, the windings are copper, yet the changing magnetic field induces an EMF in them.
    I stand by my original post, Non Metallic or to be more precise, non conductive.
     
    retiredsparks likes this.
  15. spinlondon

    spinlondon Screwfix Select

    It’s not the conductivity of the enclosure that creates the magnetic field, it’s the fact that the conductors are enclosed in a ferrous material that can become magnetised.
    Using brass or aluminium glands would would not create a magnetic field.
    Using brass or aluminium bushes with steel lock rings however woul.

    That aside, the magnetic field created in a domestic consumer unit is unlikely to cause any appreciable heating
     
    Risteard likes this.
  16. nigel willson

    nigel willson Screwfix Select

    Excuse me saying, but that’s a messssssss!!!!! I wouldn’t touch that with a large barge pole!!!
     
    retiredsparks likes this.
  17. DanielQ

    DanielQ Member

    Because people like you this is a mess...

    If I could call an electrician a get everything sorted I would.
     
  18. DanielQ

    DanielQ Member

    Thank you to all of you (including nigel_willson) for all the help.

    I took all the advises onboard and I decided to sort a few things out.

    I have managed to replace the the main earthing with a longer one. Also a a gland for the tails and earthing is now in place as I was advised by many of you.

    Wylex membranes have been installed in all the knockouts except in two(I will buy some more tomorrow)

    Because I have to live in the house while I do the work, I had to connect some lights and sockets tonight. This is a temporary thing until I get all nice and tidy.

    It would be interesting to read your comments and your advises.


    Thanks again!
     

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  19. Bob Rathbone

    Bob Rathbone Screwfix Select

    As you wish, but first go back to your college notes on Electromagnetic induction and how a voltage is induced in a conductor, Faraday's Laws will help. I do agree with you that the currents normally found in a domestic installation would not cause appreciable heating in the surrounding material that we are discussing. However their is a big 'but' here. Looking again at the principles of induced EMF, placing a ring of our material under discussion around a conductor carrying current with a changing magnetic field around it (AC) will produce a current in the ring. The current in the ring will in turn produce it's own magnetic field that will induce and EMF in the original conductor such that it will oppose the flow of current that originally produced all of this (Lenz's Law). The outcome would be similar to placing a small choke in series with the supply to the CCU, current would be limited by the action described above.
    Note to Daniel IQ, this is a technical issue that will not affect you.
     
    retiredsparks likes this.
  20. retiredsparks

    retiredsparks Super Member

    Spin.....it seems pertinent that if there was NO need for a plastic gland (as opposed to metal...conducting or not) it probably would not have been put into the regs ?
    Altho I do think the main implication is to stop the tails touching the metal units...and in TT systems causing serious problems with the main cutout....not cutting out in the event of a fault..lol

    This might help


    Rs
     

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