Hook-up question...

Discussion in 'Mech Tech' started by Lasty, Jan 13, 2022.

  1. Evenin' all ...

    Quick one for the mains electrical gurus on here . I'm mid-install and arrived at the point where I'll be connecting the twin pole RCD up but unsure about the earth connections. RCD is fitted inside a metal mounting case which is in turn mounted on wood inside a cabinet so there'll be live and neutral into and out , easy , but should the earths be connected onto the metal RCD case and then to the van bodywork ??

    Any help much appreciated. I'm ok with 12v but that mains stuff hurts if you get it wrong ...

    Sent from my SM-G960F using Tapatalk
  2. Yes, exposed metal connected to metal things with mains inside, even screw heads should be earthed and bonded to the van with a wire heavy enough to blow the fuses or circuit breakers (same size as the live/neutral, not some orrible 1mm2) . So that live to earth shorts wherever will trip something, either the RCD or a breaker on the campsite.
    Meltman and Lasty like this.
  3. Yes, connect the case to the van body.
    Dicky and Lasty like this.
  4. You need a minimum of 4mm2 green/yellow cable from the main earth terminal in the CU to the metal bodywork
  5. And the earth wires (in and out) to the metal case I presume ??

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  6. Sorry disagree with Mike

    If your talking about cross bonding then no you don’t as the Rcd will detect the imbalance as long as you have the main earth in place.

    The Circuit breakers have no part of the Earth path and only protects from overload.
  7. You should have an earth busbar in the box?
    paul2590 and Dicky like this.
  8. 4mm single cable, stranded core!
    Lasty, paulcalf, snotty and 1 other person like this.
  9. This… if it’s green and yella connect it togetha! If no bus bar then create an earth bolt to the box, fit crimps and use bolt… with paint removed of course for a good connection!
    Huyrob, matty, paulcalf and 1 other person like this.
  10. The earth connection ensures van bodywork doesn’t become live as it provides an imbalance in the rcd causing it to trip. It does also provide and earth path for any earth fault current so would user the right fault level cause the Mcb to operate but the rcd Will trip before that occurs. Or should do because the impedance (resistance) of the earth path will limit the fault current so not to be relied upon. Rcd provides your disconnection!
    Iain McAvoy, Lasty, matty and 2 others like this.
  11. Also: never stick your tongue in the consumer unit. They used to in the old days, but it’s not recommended.
    Jack Tatty, Meltman and Dicky like this.
  12. Ohhh the good old days!
    matty and snotty like this.
  13. theBusmonkey

    theBusmonkey Sponsor

    Good question @Lasty and an important safety consideration.
    I'll only take advice from the lads and lasses on here that are electrically qualified as you know.
    This was Chips earth to chassis bonding.
    It came off the common earth bus bar in the consumer unit and voilà...it would have been @Dicky and @matty approved at the time, despite the wrong coloured cable:oops:.

    I think I'd like one of the lads to have a look over the leccy system at TE coz it's always worth having stuff like this serviced or checked because it's easy to forget it's there and not see any potential faults.
  14. @Lasty

    @Dicky did a great job fitting mine correctly.

    I can get you photos of any relevant bits if helpful.
    matty and theBusmonkey like this.
  15. £80 callout charge.
    Zed and theBusmonkey like this.
  16. theBusmonkey

    theBusmonkey Sponsor

    We usually bribe @Dicky with a vegetarian chilli on the Friday night and because he doesn't drink, after all the Desperados he won't drink during the evening, I find I've got a good chance sometime on the Saturday afternoon of getting a bit of advice off him.
    Last edited: Jan 13, 2022
    Chrisd and snotty like this.
  17. I’m far too cheap!!!! Then again it’s always a very nice chilli!
    snotty, Lasty and theBusmonkey like this.
  18. Please when done as @Dicky says test continuity between metal case and van metalwork. Also on main L and N use crimp ferrules for better connection.
    Get someone to test rcd when complete with a calibrated meter would offer but.

    Sent from my SM-A127F using Tapatalk
    F_Pantos likes this.
  19. Thanks for all the answers guys - I really must get the hang of this electrickery ....
    The general consensus seems to be all earths are connected to together with the bus bar inside the RCD housing and that connected to van bodywork - thanks again

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  20. About the gist of it!
    Lasty likes this.

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