3rd Amendment Tails Entry

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

  1. DanielQ

    DanielQ Member

  2. nigel willson

    nigel willson Well-Known Member

    No all in same hole there are specific ones for tails. Ps if your doing a consumer unit u should know this
     
  3. spinlondon

    spinlondon Well-Known Member

    Should have both the live conductors and the earth in the same hole to avoid eddy currents.
    Alternatively you can use separate holes, if you cut a slot between each of the holes.
     
  4. dobbie

    dobbie Well-Known Member

  5. seneca

    seneca Screwfix Select

    As Nigel said, both need to go through the same hole. I normally use the closed grommet, just poke holes through as necessary, I find the open grommets leave too much of a gap around the cable. You can use the 32mm gland but that's only
    really necessary on TT systems to keep the tails more secure.
     
  6. DanielQ

    DanielQ Member

  7. DanielQ

    DanielQ Member

    I am not sure if this is a TT system. I have a standard meter connected to a dual RCD Metal Wylex box. The membranes that I got from Wylex are closed. The fit really really tight. It is a bit of a pain to get them in but once they are in place they don't move at all.


    So, do you think with a normal dual RCD box I don't need the tails and earthing entering together through one of this glands?

    The 32mm knockout is in the middle of the box, and It is much more convenience for me jut to go through the last 2 20mm knockouts under the main switch.


    Thank you
     
  8. seneca

    seneca Screwfix Select

    They both should go through same hole due to Eddy currents.
     
    DanielQ likes this.
  9. DanielQ

    DanielQ Member

    So it will have to entry together with a 32mm gland.

    The earthing coming out from the SSE main switch is too short. Can it be extended?
     
  10. seneca

    seneca Screwfix Select

    Yes use an earth block, they come in various sizes eg, 4 way, 6 way etc.
     
  11. unphased

    unphased Screwfix Select

    The SWA tails gland that accepts 2 x 25mm2 tails and a 16mm2 earth is 40mm dia. hole. 32mm dia gland is for 16mm2 tails. The main earth does not need to go through the same hole as the tails, its just a convenience thing. The secondary purpose of these glands is to secure the tails firmly in the CU so they can't be pulled or pushed around and they are kept secure in the enclosure.
     
  12. DanielQ

    DanielQ Member


    Shouldn't the live conductors and the earth be in the same hole to avoid eddy currents as posted above?
     
  13. dobbie

    dobbie Well-Known Member

  14. DanielQ

    DanielQ Member

  15. unphased

    unphased Screwfix Select

    No, the earth conductor plays no part in this. It has no electric current in it under normal conditions. Eddy currents are created by a law of electrics. Where a conductor passing through a ferrous metal is carrying electric current it creates a magnetic field that rotates around the hole, and heat. By putting both conductors L and N through the same hole one cancels the other so no eddy currents and no heat.
     
  16. unphased

    unphased Screwfix Select

    Don't know why people are quoting 32mm glands, clearly haven't used them yet. Its 40mm for 25mm2 tails and 16mm2 earth, as I said. I've used loads since amd3, every board I've fitted has them.
     
  17. dobbie

    dobbie Well-Known Member

    Grommet type gland I have linked to is suitable for 16mm and 25mm tails and 10mm to 16mm earth wire.
    Read the instructions before trying to **** off.
    The deleted word is the waste from a blast furnace.
     
  18. DanielQ

    DanielQ Member


    That's great news! Thank you very much for the explanation, very interesting.

    Is there any gland for a 32mm hole with 2x25mm for the tails + 2x10mm for the pipes and gas meter?

    Thanks again
     
  19. dobbie

    dobbie Well-Known Member

  20. Sparkielev

    Sparkielev Well-Known Member

    You can buy a 40mm gland with a 25mm reducer have used them loads not sure who makes think its whiska
     
    Risteard likes this.

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