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Teme iz struke » Izjednačenje potencijala u sanitarnim čvorovima

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Autor Tema: Izjednačenje potencijala u sanitarnim čvorovima 7702 pregleda
  • Janko Artuković
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    Izjednačenje potencijala u sanitarnim čvorovima Link to this post

    Da li netko ima kakav trag iz propisa ili normi koji može riješiti vječitu dilemu potrebe izjednačenja potencijala u sanitarnim čvorovima ako su instalacije izvedene PVC/PEHD cijevima ili sličnim nevodljivim materijalima???
    Voda, vodljiva, cjevi nevodljive, dileme stare i svak ima svoje mišljenje

  • Janko Artuković
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    Re: Izjednačenje potencijala u sanitarnim čvorovima Link to this post

    Evo nekih polemika po BS-u: (cijeli tekst na http://www.plasticpipesgroup.com/pdfs/earthbonding.pdf )
    In the bathroom - Supplementary Binding
    Supplementary or additional equipotential bonding (earthing) is required in locations
    of increased shock risk. In domestic premises the locations identified as having this
    increased shock risk are rooms containing a bath or shower (bathrooms) and if you
    are lucky to have one, in the areas surrounding swimming pools.
    Please note, there is no specific requirement to carry our supplementary bonding
    domestic kitchens, wash rooms and lavatories test do not have a bath or shower.
    That is not to say that supplementary bonding in a kitchen or wash room is wrong (it would be wrong for plastic pipes!) but it is not necessary.

    For plastic pipe installation within a bathroom the plastic pipes do not require supplementary bonding and metal fitments attached to these plastic pipes also would
    not require supplementary bonding.

    It seems to to be the practice of some builders to effect all the plumbing in plastic except for those bits of the pipework that are visible. These short lengths of metal
    pipework supplied by plastic pipes or metal taps connected to plastic pipes, metal
    baths supplied by plastic pipes and with a plastic waste do not require supplementary
    bonding.
    However, electrical equipment still does require to be supplementary bonded and if
    an electric shower, or radiant heater is fitted, they will require to be supplementary
    bonded as usual.
    This requirement does not apply to class II or all insulated equipment where no metal
    work that is likely to become alive in the event of a fault, is accessible. However, it is
    recommended that supplementary bonds are run to the earth terminals of all
    electrical equipment accessories e.g. flex outlets, or the equipment itself, as class II
    equipment may be replaced by class I during the life of the installation.

    1. All simultaneously accessible metal (class I) equipment (e.g. electrical heaters and
    showers), central heating pipes, hot and cold water and waste pipes require
    supplementary bonding in or close to the bathroom.
    2. Metal baths not connected to a metal building structure do not require
    supplementary bonding if all metal pipe connected to them has been connected.
    3. Connections to pipes to be made with BS 951 clamps (complete with "Safety
    Electrical Connection" label).
    Figure1: Supplementary bonding in a bathroom - plastic pipe installation
    Notes
    1. Metal (class I) items of equipment (e.g. electrical heaters and showers) require
    supplementary bonding if simultaneously accessible. Supplementary bonds to be
    connected to the protective conductors of each circuit at the accessory point.
    2. Supplementary bonding of short lengths of copper pipe(less than 0.5m in length)
    installed where the pipes are visible, is not necessary.
    There are many possible combinations of metal and plastic pipe arrangements in a
    bathroom. To try and answer questions regarding the supplementary bonding
    required in a number of permutations of copper and plastic pipe, table A has been
    prepared.
    (Pogledati taablicu A na linku)
    .......

    Notes:
    1. Supplementary Bonding is carried out to the
    earth terminal of equipment within the bathroom
    with exposed-conductive part. A supplementary
    bond is not run back to the main earth
    3. Metal baths are supplied by metal pipes do not
    require supplementary bonding if all the pipes are
    bonded and there is no other connection of the
    bath to earth
    2. Metal window frames are not required to be
    supplementary bonded unless they are
    electrically connected to the metallic structure of
    the building
    4. All bonding connections must be accessible
    and labeled "Safety Electrical Connection - Do
    Not Remove

  • Janko Artuković
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    64 postova

    Re: Izjednačenje potencijala u sanitarnim čvorovima Link to this post

    Ovdje je možda još jasniji stav i inženjerski prihvatljiviji (link http://www.alexscullion.co.uk/bs7671-2008supplementarybonding.pdf ):

    Bathrooms & Supplementary Bonding to 17th Edition (BS 7671-2008)
    Supplementary Bonding
    Supplementary bonding has been a significant feature of the 16th edition of BS 7671 but this has now changed with the introduction of the 17th edition.
    For new installations or alterations / additions in a location containing a bath or shower, supplementary bonding will not be required if:
     The disconnection times required by Section 411 of BS 7671 are met, and
     All circuits are protected by RCD’s having the characteristics required by 415.1.1, and
     The building has protective equipotential bonding in accordance with 411.3.1.2, and
     All extraneous-conductive parts of the location are effectively connected to the protective bonding. (See note below)
    Note: Regulation 415.2.2 states that where doubt exists regarding the effectiveness of supplementary equipotential bonding, it shall be confirmed that the resistance R between simultaneously accessible conductive parts and extraneous conductive parts fulfils the following condition:
    R ≤ 50V  a for a.c. systems
    By example, using a 30mA RCD (Required by 415.1.1)
    R ≤ 50V  30mA = 1667 ohms
    Where supplementary bonding is required, Regulation 701.415.2 requires that the protective conductor (cpc) of each circuit entering the room containing a bath or shower, be connected to the extraneous-conductive parts by local supplementary equipotential bonding conductors complying with Regulation group 544.2.
    This is carried out to prevent the occurrence of voltages between any such parts being of such magnitude as could cause danger of electric shock.
    Automatic disconnection of supply
    Where the protective measure ‘automatic disconnection of supply’ is used, additional protection by a residual current device, with a rated residual operating current not exceeding 30mA is required for all circuits in locations containing a bath or shower.
    Practically this means that every circuit entering a bathroom should be protected by an RCD with a rated residual operating current not exceeding 30mA. Careful consideration should be given to how circuits are divided, to eliminate the problems with unwanted tripping of RCD’s.
    SUMMARY
    With a Continuity tester on the Ohms setting, test between each metal pipe that enters the bathroom (Extraneous conductive parts) and the circuit protective conductor (cpc) of each electrical circuit in the bathroom.
    If the reading obtained is less than 1667ohms and all circuits are protected by 30mA RCD’s then no Supplementary Bonding is required.

    If any of the above requirements cannot be met, Supplementary Bonding must be installed.

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