3rd Amendment Tails Entry

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

  1. Magicspark

    Magicspark Active Member

    The regulation referred to gives dispensation when using SWA and a separate earthing conductor. I’m not sure why @Coloumb is trying to take the thread completely off topic. The opening post is clearly referring to “tails” as in single insulated and sheathed conductors, hence the bit where the opening post says about taking them through separate holes. If this is correct and I’m 100% certain this is what the opening poster is intending to do then this is not correct. The Line, neutral and protective conductor need to pass through the same hole so they are collectively surrounded by the ferrous metal.
     
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  2. Coloumb

    Coloumb Well-Known Member

    I also remain confused. AS there is no definition in 7671 as to what tails are I see no reason to take the post at face value. A meter tail is a meter tail. Wouldn't matter if it was run in flex or aluminium or if the medium was changed from meter to CU. If there is a recognized industry standard as to what defines a meter tail please post up a link.

    I therefore choose to continue to argue that it is incorrect to state that The Line, neutral and protective conductor need to pass through the same hole so they are collectively surrounded by the ferrous metal, Lee.
     
  3. spinlondon

    spinlondon Well-Known Member

    This is despite the requirement in BS7671?
     
  4. Coloumb

    Coloumb Well-Known Member

    What requirements? If you think I am in breach of them then post up the reg!
     
  5. Coloumb

    Coloumb Well-Known Member

    Don't really understand wht you mean? If you beleive tails have a correct industry recognized definition please post up a link.

    Correct. SWA is perfectly Ok for tails. If you think not post up the reg.

    Two and three core SWA. Your a spark so you must know the difference? CSA is the CSA of the equivalent steel csa compared to copper. The requirement being to provide the correct CSA protection for a fault. You don't get this? Zs is the total impudence of a ctt. You must know this? Am I being too technical for you?

    Because it has been incorrectly stated that this is the case under 7671 with tails. It is not. If you think it is post up the reg.

    It's in the cut out. I have stated this twice.
     
    Last edited: Oct 11, 2018
    unphased likes this.
  6. Magicspark

    Magicspark Active Member

    139A2741-66BA-486A-B15E-99ACA081308E.jpeg
    TBH I’m not surprised you are confused....from what I’ve read it doesn’t take much for you to reach that state! No there is no definition in BS7671 you are correct. However “meter tails” is the non technical term, often used, referring to single insulated and sheathed conductors that connect to the meter. http://lmgtfy.com/?q=Meter+tails
    This is obviously way beyond your mental capacity....Do you go into a wholesaler and ask for meter tails and expected to be given steel wired armoured cable....I think not.
    Regulation 521.5.1 requires where conductors enter a ferrous enclosure they shall be arranged such that the conductors are collectively surrounded by ferromagnetic material.

    This requirement includes an SWA cable but in this situation where an additional protective conductor is required it is permitted for the additional protective conductor to enter the ferrous enclosure individually.

    It’s in black and white, You don’t have an argument....you just don’t agree with what’s written in 521.5.1

    Keep arguing/digging a hole for yourself as I find it very amusing...I’m sure the others that have joined in on this thread do as well o_O

    Edit: this is the pic the opening poster has posted up in this thread clearly showing single insulated and sheathed conductors passing through as what’s referred to as a tail gland....I don’t see any SWA, do you?
     
    Last edited: Oct 11, 2018
  7. spinlondon

    spinlondon Well-Known Member

    I’m saying tails is just a word used to describe the conductors connected to a meter.
    I’m not aware that there is any industry recognised definition.
    Again there is no specific Reg. there’s only a requirement to provide fault protection.
    I’m well aware what it means, just don’t understand why you’re going on about it?
    521.5.1 AC circuits: electromagnetic effects Ferromagnetic enclosures: electromagnetic effects
    The conductors of an AC circuit installed in a ferromagnetic enclosure shall be arranged so that all line conductors and the neutral conductor, if any, and the appropriate protective conductor are contained within the same enclosure.
    Where such conductors enter a ferrous enclosure, they shall be arranged such that the conductors are only collectively surrounded by ferromagnetic material.
    These requirements do not preclude the use of an additional protective conductor in parallel with the steel wire armouring of a cable where such is required to comply with the requirements of the appropriate regulations in Chapters 41 and 54. It is permitted for such an additional protective conductor to enter the ferrous enclosure individually.
    So you have permission from the Distributer to use their cut out to protect your tails?[/QUOTE]
     
    Last edited: Oct 11, 2018
  8. Woloumbo

    Woloumbo New Member

    This guy has issues.

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  9. unphased

    unphased Screwfix Select

    As I see it the main earth conductor is NOT a circuit protective conductor, it is the MAIN EARTH conductor which is provided for the installation. It has nothing to do with the tails. Tails are separate L and N supply conductors to the meter and the DB or CU and there is no circuit protective conductor associated with them as far as I am concerned. If you happen to use an SWA as a main supply tail in to an enclosure you are at liberty to use one of the cores as the main earth conductor, or the SWA armouring, or run a separate main earth conductor in to the enclosure. The main earth conductor is not protecting the meter tails it is part of the entire ethos of BS7671 which is ADS and without an earth system the whole thing falls apart. Take time to read the words and digest. It is the manufacturers of these items who are as culpable as anyone else misinterpreting regs. Since when has a pair of meter tails or supply tails ever been associated with a cpc? You dont see earth wires looping in and out of a meter do you? Or looping in and out of Henley blocks? The main earth conductor can go through any hole you feel like using in to a DB or CU. It has no consequence whatsoever on eddy currents, protecting tails, or any thing else other than providing the actual connection to earth be it TN-S, TN-C-S or TT, it really doesn't matter. So you don't have to put the main earth conductor through the same hole as the meter tails, that is totally unnecessary.
     
    Last edited: Oct 11, 2018
  10. Bob Rathbone

    Bob Rathbone Well-Known Member

    A neutral one third of the size of the phases? Count the conductors.
     
  11. Bob Rathbone

    Bob Rathbone Well-Known Member

    "Protective" not circuit protective, their is a difference.
     
    retiredsparks likes this.
  12. unphased

    unphased Screwfix Select

    But the main earth conductor is not in any way solely associated with the main tails. They are mutually separate and do NOT need to be grouped together in to one hole. What difference does it make where the main earth conductor enters an enclosure? It is ludicrous to even suggest it must go through the same hole as the tails. Why? If it is convenient or neat then no problem, but there is no actual requirement to do it. What possible technical reason can you think of for doing it? I can't think of any. The function of the main earth conductor is completely independent to any other conductors and there is no detriment to the system as a whole wherever it enters an enclosure.
     
  13. Bob Rathbone

    Bob Rathbone Well-Known Member

    I am not disagreeing, just trying to point out he difference. See my earlier posts in this thread on Lenz's Law and it supports your point as the inductive ring (hole) around the earth conductor may reduce earth fault currents.
     
  14. Bob Rathbone

    Bob Rathbone Well-Known Member

    Just had another look at the photo, cable ties are insufficient restraint on cables carrying this much current. During short circuit faults, the cables will be pulled away from the flimsy ties by the powerful magnetic forces created.
     
  15. spinlondon

    spinlondon Well-Known Member

    Yes.
     
  16. spinlondon

    spinlondon Well-Known Member

    Sorry, that’s the 11kV side, and the photo was taken before clamps were put on.
     
  17. spinlondon

    spinlondon Well-Known Member

    Sorry, but any earth fault in the insatallation will cause current to flow through the Supply Line conductor and the installation earth.
    If they enter a CU constructed from ferrousmagnetic material via different holes, eddy currents will be produced.
     
  18. Coloumb

    Coloumb Well-Known Member

    [/QUOTE]

    I really don't know why I have to keep explaining this to you. What don't you understand?

    It's this simple. You take the pvc tails out of the meter, connect them to an adaptable box, then gland your swa off the box. If you use two core then you can either use the steel as the main earth or use two core and a separate earth. If you use a separate earth then you can put this in a different hole to the main conductors. This complies with 7671 either way. Ergo sum, it is incorrect to say that the earth has to be in the same hole as the conductors for the tails. Clearly this isn't the case.

    I don't know what you mean about the distributor? What permission? If you need permission from then what law's are in place to provide the framework?

    For the last time, protection is from the cut out fuse so long as it's within the required Zs. This can be calculated by using the correct test equipment and comparing to the relevant chart showing the characteristics of the fuse in the cut out.
     
    Last edited: Oct 11, 2018
  19. Coloumb

    Coloumb Well-Known Member

    Have you actual read the regulation? Where does it say specifically that SWA tails are excluded?

    I don't, but I bet you do.
     
    Last edited: Oct 11, 2018
  20. Magicspark

    Magicspark Active Member

    Yes I have read it and I’m fully conversant with it, that’s why I pointed the regulation out. You seem to struggle to comprehend something some basic and have gone off on a tangent about SWA....The opening post and others posts made no reference to SWA what so ever..I’ve also pointed out to you that the regulation does not preclude the use of SWA and a separate earthing conductor for that circuit entering through a separate hole to that of the SWA....You are digressing from the Op and subsequent posts to try and make an argument. The matter of fact is you’ve been shown up for what you are throughout this thread and it’s rather embarrassing for you.
     

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