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  1. Thomas Connolly
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    Thomas Connolly Regular EF Member

    Location:
    Kent
    Hi Folks,

    If I'm extending a lighting circuit, (adding two pendants and an outside light) from an existing pendant but the board doesn't have any protection (an old BS3036 fuse board) What's the best way to add RCD protection?

    The new cable for the switches can't buried more tore than 50mm deep and I don't want to whack an RCD FCU anywhere as they are quite bulky.

    What would be the best course of action to take to install this circuit so it complies with the Regs?

    Thanks,
    T
     
  2. SparkyChick
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    SparkyChick Making a banana smoothy for my fave gorilla Staff Member Moderator

    Location:
    South Wales
    Business Name:
    SparkyChick
    RCD FCU at the origin? Standalone RCD in an enclosure at the origin?
     
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  3. spinlondon
    Offline

    spinlondon Forum Mentor

    Location:
    Harlow Essex
    Install an RCD in an enclosure next to the fuse board.
    Feed the RCD from the lighting circuit fuse and then feed the lighting circuit from the RCD.
     
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  4. Fitzy
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    Fitzy Newly Qualified Sparky Electrician's Arms

    Location:
    Redhill
    Business Name:
    DF Electrical Services
    You could install a 3 module consumer unit fed from your 3036 board, then install an RCD and 6a mcb for the lighting circuit in this cu, which is notifiable work.

    But, by the time you’ve gone to all that effort for just 1 circuit, you’d be better off upgrading the complete board and protecting the whole house.
     
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  5. GBDamo
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    GBDamo Regular EF Member

    Location:
    UK
    You forgot...

    ..and pray to god the existing circuit is fault free.
     
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  6. GBDamo
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    GBDamo Regular EF Member

    Location:
    UK
    If done SpinLondon,s way would it still be notifiable? the OCPD at the origin of the circuit would be unchanged, only addition of additional protection.
     
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  7. Thomas Connolly
    Offline

    Thomas Connolly Regular EF Member

    Location:
    Kent
    I figured the RCD FCU at the origin would be the simplest solution.

    As the old Wylex Fuses for lifting circuits are rated at 5a... What size fuse would I put in the RCD FCU? A 3a?

    I believe there are currently 4 pendants on the circuit.

    I don't think it would be notifiable because i would just be adding a fuse on the existing wiring, it just happens to be next to/near the fuse board?

    Correct me if I'm wrong.
     
  8. spinlondon
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    spinlondon Forum Mentor

    Location:
    Harlow Essex
    I would see it as an alteration to an existing circuit.
     
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  9. Taylortwocities
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    Taylortwocities Electrician's Arms

    Location:
    Oxfordshire
    You need to get your discrimination tables out to answer that one!
    My gut feel is that it won't discriminate.

    But, whoa fella. Why an RCD FCU?. Just install an RCD.
    You do not need any additional fusing.
     
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    Last edited: Feb 11, 2019
  10. Welchyboy1
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    Welchyboy1 Electrician's Arms

    Location:
    Essex
    Leave it as 13a
     
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  11. GBDamo
    Offline

    GBDamo Regular EF Member

    Location:
    UK
    I would say the fuse is largely irrelevant as it is not needed to provide protection, the fuse in the DB is doing that.

    All yo really want is an RCD.

    Slap a 13A in it.

    If such a beast existed, you could fit a non fused RCD spur.

    Tin hat on.
     
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  12. spinlondon
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    spinlondon Forum Mentor

    Location:
    Harlow Essex
    Circuits supplying luminaires now require 30mA RCD protection.
     
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  13. Taylortwocities
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    Taylortwocities Electrician's Arms

    Location:
    Oxfordshire
    Sorry. I meant to say you just need an RCD. I’ve edited my post. :oops:
     
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  14. Thomas Connolly
    Offline

    Thomas Connolly Regular EF Member

    Location:
    Kent
    I just thought it would be cheaper and simpler to just add an RCD FCU would it now?

    Just means I can split the existing cable, add the RCD FCU in between and be done with it?
     
  15. spinlondon
    Offline

    spinlondon Forum Mentor

    Location:
    Harlow Essex
    One of the problems with that idea, is the requirement is to provide RCD protection for the circuit, not just part of the circuit.
     
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