equipotential bonding-need for in structural steel install.

Discussion in 'Electrics UK' started by andy1984, 31 Jan 2008.

  1. andy1984

    andy1984

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    hi guys, after a bit of advice and opinions of the best course of action to take.
    not really a DIY question but there are some good sparks on here who may be able to help.

    sorry if the post gets a bit long but here goes......

    got an installation (factory) with a 3 phase supply (400A). tpn switchfuse as the main switch which feeds a busbar chamber which feeds other dbs and things. this is all located in a main switchroom. the chamber & s/f's are mounted onto a perpous made metallic frame. also bolted onto this frame is a solid copper bar with various earth cables going off out into the factory( this looks like its meant to be the MET)

    the main gas/water pipes run through this room but the services actually enter the building about 60 metres away.

    from the corner of the framework (supporting the chamber and s/f's) is a solid copper bar that twists onto the gas pipe. (no labels at all, 951's ect) but its purpose can only be to equipotentially bond i would think.

    no other bonding present anywhere along the gas or water pipes. the building is a mass of structural steelwork with pipes (gas and water) bolted onto the steelwork beams at many many various places.

    as im upgrading i figure the equipotential bonding needs looking at..... here is where advice is needed.

    in affect the installation is fully bonded by the nature of its construction, it just doesnt have 951 labels or earth cables to services.

    1, would others run earth cables just for the sake of it. the solid copper bar on the frame is 'full' so i can either run from the frame or mount a new bigger MET.

    2, to run cables to the point of entry would be a very difficult run. the regs say 'where practicable' this should apply. what others views on me running to the services within the room. its a fully metal system by the way (no plastic pipe)

    3, the pipes are quite thick (50mm water and 80 mm diameter for gas). where would i obtain suitably big 951 clamps and labels for this purpose. the way i read the regs i need a 25mm copper earth cable only as its a TNS system.

    regards and thanks for your time.
     
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  3. Spark123

    Spark123

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    The pipes should really be bonded as close as practical to where they enter the building. Is 60m away really as close as practical?
    It may be possible to use the steelwork as part of your MEB run providing the criteria in BS7671 are met.
     
  4. andy1984

    andy1984

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    hi spark 123,

    probably not the most practible no, but definetly the easiest ;)

    in all seriousness though it will be a difficult run to where the services enter the building (both in different places)- plenty of drilling and messing about.

    as with a lot of things though if it must be done it must be done.

    just seems a little pointless as its only going to achieve something asthetically pleasing on the eye.
     
  5. DIYnot Local

    DIYnot Local

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