use a twin and earth as a three core

Discussion in 'Electricians' Talk' started by Brizzo, Apr 10, 2015.

  1. Brizzo

    Brizzo New Member

    Hi all
    Bit of a strange one , been asked to put a fan in a bathroom in a block of flats,the cable is conduit in concrete ceiling and I can't thread or access from above .a solution would be to take power off the pull switch by the door through wall to isolator back through to wall and run it round the edge of the room in flat trunking .but I need a neutral . So my question is can I put blue sheathing on the earth wire in cable to light switch on both ends and use that as neutral ?.which would give me the live,switched live and neutral for a double insulated timed fan
    Brizzo
     
  2. FatHands

    FatHands Well-Known Member

    no mate - the line conductors must be the same CSA. If you use the earth as a neutral it will be smaller than the line
     
  3. Brizzo

    Brizzo New Member

    Thank fats
    Not thought of that!
    Can't do it anyway ,disconnected earth at light end and it's still got earth continuity
    But thanks for quick reply
     
    FatHands likes this.
  4. retiredsparks

    retiredsparks Super Member

    Nice one Fats.
    RS
     
    FatHands likes this.
  5. Lectrician

    Lectrician Screwfix Select

    The earth is not double insulated, so no. In 1mm T&E, the earth is the same size.

    I found this during a PIR a few years ago. Ironically, the brown could have been used for both switches.

    [​IMG]
     
  6. What harm can it do, give it a go
     
  7. Rulland

    Rulland Screwfix Select

    Oh my.
     
  8. Lectrician

    Lectrician Screwfix Select

    There's no doubt it would work, but that doesn't make it right :rolleyes:
     
  9. unphased

    unphased Screwfix Select

    No basic insulation on an earth wire. Very dangerous and a definite must not do!
     
  10. You've done it in the past roy
     
  11. nigel willson

    nigel willson Screwfix Select

    rewire in mini trunking? do it properly
     
  12. Welshdragon1

    Welshdragon1 Active Member

    From that I would never employ you, as this is obviously dangerous practice as mentioned above

    & mentioned below you message

    Cliffy, please go & read the basics on safe wiring practices, as even non sparkies are most likely to know that it is a defo NO-NO
     
    Cliffy T Brown likes this.
  13. chippie244

    chippie244 Super Member

    Don't feed the trolls, leave the trolls alone.;););)
     
    Cliffy T Brown and Welshdragon1 like this.
  14. Welshdragon1

    Welshdragon1 Active Member

    The trolls should not be fed after midnight, or does that only apply to gremlins ?? ;) ;)
     
    Cliffy T Brown likes this.
  15. unphased

    unphased Screwfix Select

    Its been a while since our cliffy graced the forum with his presence.
     
    Cliffy T Brown likes this.
  16. I missed helping people
     
  17. MGW

    MGW Screwfix Select

    I was under the impression for years that one could not over sleeve an earth wire. However on very careful reading that is only with singles it would seem you can over sleeve the earth wire of a flex. I would still not do it though. As to twin and earth if it was in conduit or trunking at 1mm then it would be a grey area. (Not talking about cable colour) I would never do it myself, but as to failing some one else's work I would have to consider carefully. However bare copper should never show, so the picture shown is clearly wrong. Had they used brown sleeving one would need to see the cable run. However we should always provide an earth even if not used. This has been the case since around 1964 when the rules were changed with lighting. So with say three twin and earths like seen with some old central heating, using one of the earths as a live just may scratch into the permitted box, if over sleeved, and run in conduit or trunking. But to date I have never seen a twin and earth earth wire used where it could possibly be considered to comply. To date every one seen has not complied for some reason.
     
  18. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    I was under the impression that it was written in the big book that the Earth wire should NEVER be used as a live conductor under any circumstances!

    Mr. HandyAndy - Really
     
  19. chippie244

    chippie244 Super Member

    By a very long way :cool::cool::cool:
     
    Cliffy T Brown likes this.
  20. unphased

    unphased Screwfix Select

    I know it's not directly on topic, but, I wonder why cable manufacturers continue to make cables without basic insulation on the cpc?

    The point about a cpc is it is not a live part. If an idiot wants to make it a live part then it contravenes Regs because all live parts need at least basic insulation or must be placed out of reach (bus-bars for example). Does a sheath of a cable count as basic insulation under the definition? The sheath on a T&E is just holding the conductors in place to form a continuous cable and provides some protection against scuffing during installation.
     
    FatHands likes this.

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