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Discuss Mains box to Consumer unit SWA or tails? in the Electrical Forum area at ElectrciansForums.co.uk.

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  1. grandfortune
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    grandfortune Solar Guru

    Location:
    Midlands
    HI all,

    usually take tails form a MEB box to consumer unit no matter what the length as long as i can get the 50mm depth, builder has told me he wants it in SWA, ive told him its pretty much impossible to terminate it right if i use SWA also i run up the cavity with the tails and there is no way i can get SWA up there so will have to run inside up the wall which i hate doing, what do you guys do if using SWA??

    Cheers
    Grand
     
  2. grandfortune
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    grandfortune Solar Guru

    Location:
    Midlands
    like the look of split concentric??
     
  3. buzzlightyear
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    buzzlightyear Electrician's Arms

    Location:
    star command
    is this to a flat?
     
  4. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    Split concentric is no longer deemed suitable for use in walls without additional rcd protection, no idea why this is now the case.
     
  5. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    It is the case because it doesn't have an earthed armouring. The earth strands only surround a third of the core, the other two thirds is the neutral.
     
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  6. grandfortune
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    grandfortune Solar Guru

    Location:
    Midlands
    mmmm thats interesting, so surly tails isn't suitable then as the earth is totally separate?, SWA it is then

    its a domestic house btw


    how do you terminate the armored in the mains cupboard, and fook me it will look ugly terminating it into the board.
     
  7. Des 56
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    Des 56 Trusted Advisor

    Location:
    Gliese 581C
    Could you terminate the swa into a metal box directly under where the consumer unit is mounted and connect direct ? If not can you use a adaptable box butted up to the consumer unit, gland into that with the cores straight through
     
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  8. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    Are you talking concentric or split concentric because I have often wondered as originally it was deemed acceptable.
     
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  9. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    Advise the builder that if he wishes to do the electrical installation design then he will have to sign the EIC for design and accept the liability.

    One method of terminating SWA in a meter box is to fit the gland to a short piece of brass angle, then heatshrink the cores with adhesive lined heatshrink to give protection and again heatshrink over the breakout.
    This should give you an idea of what I mean, though in this case the bedding is stripped within the gland and the gland filled with epoxy to seal it.


    IMG_2930.JPG
     
  10. Dave OCD
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    Dave OCD Electrician's Arms

    Location:
    Cornwall
    Business Name:
    Hendry Electrical Services
    But if this is a new installation the board itself will be steel and you'd gland straight into it.
     
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  11. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    Terminate the SWA into a metal flush box behind the CU
     
  12. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    It will only look ugly if you make it ugly.

    Terminate the SWA into the flush box you fit behind the CU the same as the outgoing circuits.
     
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  13. bigspark17
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    bigspark17 Electrician's Arms

    Location:
    wales
    Terminate it into a metal switch fuse isolator as you would use if the cu was >3M away.. you could float it into the back of the board without a gland if the swa was soundly cleated to provide protection of cable being dragged back & that the swa was bangod correctly supply end and a 3rd inner core was used inside the swa, it may be frowned upon & i would only do this as a last resort.
     
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  14. Dave OCD
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    Dave OCD Electrician's Arms

    Location:
    Cornwall
    Business Name:
    Hendry Electrical Services
    Ah the upside down Switchfuse is back. :D
     
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  15. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    Bolt an adaptable box to the back using the lid fixing screw points.
     
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  16. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    I mean split concentric, the requirement for buried cables is that they have earthed armour or sheath etc. Split concentric doesn't satisfy this.

    I don't know if it was ever deemed compliant for burial in a wall without RCD since that rule came in.
     
  17. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    Yeah, it annoys the hell out of me, but I thought it better to have the incoming and outgoing the right way round rather than the switchfuse the right way up.
     
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  18. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    Yeah, it annoys the hell out of me, but I thought it better to have the incoming and outgoing the right way round rather than the switchfuse the right way up.
     
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  19. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    Plastic switch fuse, why not metal?
    Or is this not recent?
     
  20. Leesparkykent
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    Leesparkykent You Rock Gmes Staff Member Trusted Advisor

    Location:
    Kent
    Use 16mm twin and earth and seperate 10mm green and yellow with mechanical protection where it runs down the walls.
     
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  21. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    its not particularly recent, But if I was to do the job today I probably wouldn't change it for metal and would record it as a departure on the EIC.
     
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  22. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    Why not metal ? You could gland straight into it
    Also explain how it's a departure and not a non compliance?
    It's not a consumer unit but I'd put it as a similar switch gear assembly
     
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  23. Leesparkykent
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    Leesparkykent You Rock Gmes Staff Member Trusted Advisor

    Location:
    Kent
    Personally I feel the KMF is the wrong choice for the job in the above pics due to it having to be installed upside down as the load side is at the top..I would of opted for something different or done the job differently if nothing else would fit in the cab.
     
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  24. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    A departure is a non compliance, if it complied then it wouldn't be a departure.

    At the time there was no suitable metal option.
    Now I am still not aware of a suitable metal option, bearing in mind it is in a meter box so steel is not suitable because it will rust.
    The KMF is made of a Bakelite type plastic which to the best of my knowledge is not readily combustible in the way that the soft plastic used for CUs is.
    It is located outside of the building and presents no greater risk than the other plastic equipment installed in there (meter, cutout, Henley block)
     
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  25. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    To depart is to install or use something that is no less safe than full compliance with bs 7671 so if bs7671 calls for non combustible enclosure on a consumer unit or similar switch gear assemblies and you don't adhere to the regulations then it's a non compliance to me and not a departure
     
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  26. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    It only had to be installed upside down because I'd made off the cable and fitted the KMF the right way up before I realised my mistake.
    Had I paid a bit more attention it would have been done differently the KMF would be the right way up.
     
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  27. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    If you decide to record a departure then the level of safety should not be less than obtained by compliance with the Regulations. It can be difficult to prove such things. DSs explanation in #24 does have validity that the enclosure is more likely to char than ignite but whether its level of safety is less could be debated. The only thing I would comment on if I undertook an EICR is that it is upside down :D
     
  28. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    Yes well as the designer I deem this departure to be no less safe than compliance with that particular regulation.
     
  29. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    Touché
     
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  30. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    I'd question it being upside down too, I wasn't very happy with that when I fitted it but I'd dug myself into a hole and had to get out of it.

    This has got me wondering whether GRP would be considered non-combustible
     
  31. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    Thinking about it further I wonder if GRP is non combustible? If so then it could be argued that it does comply.
     
  32. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    It's a fair point.
    I wonder if any tests have been carried out.
    After all there's electrical equipment installed inside so would it have to have some flame retardant qualities?
     
  33. suffolkspark
    Online

    suffolkspark Electrician's Arms

    Location:
    suffolk
    I've put metal switch fuses in meterboxes before but used the protek ones as there not too big, gland the swa into it then gland it into the metal ccu if possible, if its in a cupboard id just bring the armoured out and go surface into the bottom of the ccu, provide a pot of white paint if the customer doesn't like the look of it :)
     
  34. suffolkspark
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    suffolkspark Electrician's Arms

    Location:
    suffolk
  35. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    As I said in #27 it is likely to char and not propagate any flame. These materials can have differing make up some of which do have fire resistant properties.
     
  36. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    I'm referring to the metre box which is made of GRP (fibreglass)
     
  37. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    It maybe argued that the meter cabinet is outside the scope of bs 7671 so can't be used in the sense of a non combustible enclosure as bs 7671 sees it, then its maybe a departure which goes back round to what dave said but only slightly different reasoning.

    Anyone still listening zzzzzzzzzzzz
     
  38. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    If I hadn't lost the picture of the one I did before the non combustible rule came in then I wouldn't have posted that one.
    Plus the KMF wouldn't have been upside down.
     
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  39. bigspark17
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    bigspark17 Electrician's Arms

    Location:
    wales
    I think kmf are ok in a surface mount DNO box outside the property but shouldnt be used in a recessed one as its sitting inside the cavety of the house so as electricians must use the best advice giving to us by bs7671.
     
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  40. buzzlightyear
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    buzzlightyear Electrician's Arms

    Location:
    star command
    sorry I think the lads have runner away with this, he only wants to know.
    if he can use SWA concentric wiring. and the best way around it
     
    Last edited: Jul 16, 2017
  41. buzzlightyear
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    buzzlightyear Electrician's Arms

    Location:
    star command
    I bet he has gone to bed with a headache after reading that lot.
     
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  42. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    I've finally found some of the pictures i was looking for earlier. This job was done in early 2015 so had a completely legitimate plastic CU fitted.

    This is what I mean about the flush box behind the CU
    IMG_1985.JPG

    And this is the supply end in progress, I can't find any pictures of it finished but you get the idea, and the KMF is the right way up!

    IMG_1907.JPG
     
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  43. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    Ferrous box with live and neutral going through separate holes?

    Edit going through timber or something else rather? thought I'd caught you out dave :)
     
  44. buzzlightyear
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    buzzlightyear Electrician's Arms

    Location:
    star command
    no shroud on SWA covering the brass locking nuts .
     
  45. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    It's a piece of paxolin,
     
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