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pictures of a recent job

Discussion in 'Electrics UK' started by rjuk, 9 Jun 2008.

  1. plugwash

    plugwash

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    It looks pretty tight but not any tighter the the preformed elbows you can buy.
     
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  3. RichardPW

    RichardPW

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    What worries me is the UNFUSED 13A plug :eek: that you've got in one of those sockets. I had some of those arrive last year on the end of IEC cables for some computer equipment. Eeek...
     
  4. SparkyMarky

    SparkyMarky

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    Well I'll give you a complement if no-one else will! It may not be perfect, but it looks a tidy enough job to me. It's certainly better than 99% of the setups you'd find in a garage... :)
     
  5. comms

    comms

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    Exported PME via armour?
    Got to agree with lack of saddles comments, but does look tidy enough.
     
  6. Spark123

    Spark123

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    Don't know if it is TN-CS, there are no MEBs present so I take it there are no extraneous conductive parts i.e. metallic water pipes. 6mm 2c XPLE SWA complies with table 54G for use as a CPC.
     
  7. jason1958

    jason1958

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    Reasonable job for a DIYer, a bit "quick" for a pro.

    Some regs will help you here, from OSG, Brown, 16th BS7671.

    1. Armoured cable cleat spacing (p103)
    - Armoured 9-15mm - Horizontal 350mm, Vertical 450mm
    - Armoured 15-20mm - Horizontal 400mm, Vertical 550mm
    - Table 4A - "Spacing of supports for cables in accessible positions"

    2. Rigid Conduit clip spacing (p106)
    - Rigid 16-25mm - Horizontal 1.5m, Vertical 1.75m
    - Table 4C - "MAXIMUM distance between supports for conduits"

    The table lists the maximum & does not consider bends.
    Bends require more clips to prevent conduit hinging away from wall.

    3. Conduit bend radius (p106, Table 4C, Note 3)
    - Generally the inner radius should not be less than 2.5x its o.d.
    - That is strictly for flexible, but good practice

    Conduit bend radius is for ease of drawing cables in.
    - 6491X singles <10mm o.d. bend radius typically 2-3x D(iameter), Table 4E p108
    - 6491X singles >10mm o.d. bend radius typically 3-4x D(iameter), Table 4E p108
    - SWA bend radius typically 8x D(iameter), Table 4E p108


    General comments.

    Conduit drains...
    - Conduit drains back to the CU & SWA Armour point
    - You need some drain holes at the lowest point (if not already present)
    - This does compromise the IP rating, but not beyond that already (nothing there is splashproof)

    Conduit cable...
    - I assume 6491X used for conduit singles not stripped flex/FTE?
    - 6491X has thicker insulation for conduit applications

    Two final circuits sharing conduit...
    - Nothing wrong with that - labelling can be helpful (dymo rhino).

    SWA...
    - Earthing PME is an issue here
    - Export PME = Building of wood + raised on wood sleepers + Class-1 tools used + no incoming metal services
    - TT & Earth-Rod = Building of concrete or concrete floor or Class-1 tools used or incoming metal services or accessible metal structure in contact with the ground or caravan

    Suspect this should really be a TT installation.
    - If you decide to TT it, you must make sure there are no drains below
    - Not just yours, but other peoples (on your land), railway, etc

    PVC glue for conduit
    - never apply with cables in place (obviously)
    - mostly useless with black conduit in clips as a summer/winter cycle breaks the seal (like black guttering, black plastic expands & contracts enormously with temperature hence the importance of slip joints with long runs of conduit)
    - hence a flexible sealant can be more useful


    Only real issue is exporting PME earth :D
     
  8. Spark123

    Spark123

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    What is the issue of exporting the PME earth where there are no Extraneous CPs , making the assumption it is TN-CS?
     
  9. rjuk

    rjuk

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    Thanks for the comments.

    I have glued all joints and there are drain holes in the lowest parts of conduit. The installation in the house is TN-S and the actual house is no more than 10 metres away.

    All cables are stranded singles.

    This weekend I'll add some more saddles as I agree it is likely to start to sag.
     
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  11. jason1958

    jason1958

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    Difference in "earth" potential.
    - House PME is at potential X.
    - Garage concrete floor is at potential Y.

    Standing on the garage floor (potential Y) and hold the garage metal CU (potential X) may result in a potential difference across your hands & feet.

    Admittedly this is more likely if the garage is some distance away (local "earth" differs from PME "earth").
    Admittedly this is more likely with a bad house neutral (and why house MEB must be correct in terms of both present, conductive & right CSA).

    However the idea is to have all "earth" potential at the same potential, you are introducing house-PME potential into a damp concrete garage with metal CU.


    Had a closer look at the photos.
    Only (mild!) criticism is the exported PME & 2 conduit clips needed.

    When the job is done, pull back the conduit near a bend, fit a 1-hole snap-over clip & snap it back. Mainly in case someone wields a ladder in a garage and snags the conduit which is only fixed remote to the bend allowing it to "hinge". The 16th should have used the term "spaced such that conduit on at least one side of each bend is supported".
     
  12. Spark123

    Spark123

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    You can say the same for inside the house though, the difference in potential would depend where the last PME connection is on the system, the current flowing in the system and the resistance of yourself to mother earth. Unless you are going to install a bonded metal grid in the floor that is, which in some instances is recommended i.e. shower blocks.

    You can say the same for using a class 1 appliance fed outside via an extention lead from the house. This is a bad scenario when you are in direct contact with mother earth.

    Appologies to the OP for the hijack, this isn't really relevent as your system is TN-S, not TN-CS (PME)
     
  13. comms

    comms

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    Thats why I ended my sentance with a ? because I didnt know if the system was pme or not & didnt have the calc sheet to hand with regard to armour of 6mm as cpc.
     
  14. oharaf

    oharaf

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    I quite like it!

    More saddles yes definitely, people and objects can easily remove this stuff.

    Iwas always told saddle before and after a bend, and then try with your hand for deflection along the lengths if it moves more than half a cm put a saddle on it!!
     
  15. shetland

    shetland

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    What if the garage is connected to the house (built on the end) with a concrete floor? It is conceivable that a garage built on the end of a house could actully be further away from the MET than a detatched garage, depending on the loction of the incoming supply. Would you then regard the garage as being the same equipotentil zone?



    Neat bit of conduit, save for the clips :)
     
  16. ban-all-sheds

    ban-all-sheds

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    Of course he would.

    Surely you realise that he thinks walls have some kind of magical electrical properties?
     
  17. ezekiel

    ezekiel

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    stupid question time:

    how you bend plastic conduit? dont it just break?
     
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