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OSG 7.3.2 cables in walls and partitions

hertzal123
In the above,item d states the cables can be protected by earthed steel conduit or,

Item e then states :mechanical protection sufficient to prevent penetration of nails,etc,

but no mention of earthing..

I have a situation with a short 200mm horizontal run outside the zones.

I could slide a lenght of earthed conduit over,but then the earth connection would be plastered

over and could not be inspected.

If I treat the conduit as mechanical protection,it would not need earthing?

Wondered what others would do.

                                                        Regards,Hz

  • 0

    Presumably it has been tested for occasions where a nail may just penetrate the aluminium covering part and touch the phase conductor as well. Or is the cable only compliant for burying out of zones if the C.P.C. is also touched by the invading nail?





    I believe the BS 8436 test involves a 1.6mm dia nail connecting just the foil to a line conductor - e.g. https://www.fpcables.co.uk/6_NAIL_PEN.pdf


    Presumably the situation is helped by the foil being in contact with the entire circumference of the nail and then (a bit like the soil surrounding an earth electrode) the effective c.s.a. of the foil gets significantly larger quite quickly as the current moves away from the nail.


       - Andy.

  • 0
    An enquiry about B.S. 8436 cable in Screwfix today resulted in blank looks by the staff as did an enquiry about 100 Amp. B.S. 88-3 cut out fuses.


    Z.
  • 0

    An enquiry about B.S. 8436 cable in Screwfix today resulted in blank looks



    Must have been new staff - they used to stock it a few years ago.


      - Andy.
  • 0
    At that price they prob only sell a drum every 5 years.Hz?
  • 0

    Flexishield logo
    Developed for use in partitions and building voids

    Flexishield cable



    Flexishield has been specifically developed for applications where cables are required to be concealed within partitions and building voids, at a depth of less than 50mm.



    Flexishield’s main feature is it’s ability to fail safe when used as part of an electrical circuit that is penetrated by a sharp metallic object. The cable has now been designed to fail safe at 200 amps under nail penetration conditions, as such it will operate an MCB of up to 40A Type B or up to 20A Type C this surpassing the requirements of BS8436.  A fully compliant cable, Flexishield is a cost effective solution to meet the 18th Edition of The Wiring Regulations BS 7671:2018 for concealed cables at a depth of less than 50mm, Regulations 522.6.201 to 522.6.204.



    Flexishield is a protected fixed wiring cable, it uses a bonded aluminium tape which gives excellent mechanical resistance and acts as an effective screen to help reduce electrical interference. Flexishield has been independently certified to BS 8436 (300/500v) and IS 273 (600/1000v) by BASEC.



    The Range



    Flexishield as standard comes in the range of 1.5 to 4.0mm2 to BS 8436 300/500v and the 6.0mm2 to IS 273 600/1000v. All available with stranded conductors of 2, 3 and 4 cores and a CPC of equal cross sectional area. Standard sheath colour is white, core colours as per the harmonised wiring codes and supplied on 100m drums. Options by request are available with sheath and core colours, drum lengths and 600/1000v ratings on the 1.5 to 4.0mm2 sizes.



    So do we just connect the C.P.C. to an earth terminal as usual? Or do we have to gland the cylindrical foil in any special way?


    Z.


  • 0

    hertzal123:

    At that price they prob only sell a drum every 5 years.Hz?




    I suppose that if it helps compliance and reduces labour time it is a good investment.


    Z.

  • 0

    So do we just connect the C.P.C. to an earth terminal as usual? Or do we have to gland the cylindrical foil in any special way?



    Just sleeve and terminate the c.p.c. - as you would for T&E. No glands required (although normal round glands can be useful where an improved IP rating is needed). The foil is in contact with the c.p.c. all along the cable, so connection to the foil is automatic.

      - Andy.
  • Former Community Member
    0 Former Community Member

    Chris Pearson:

    But I think that this is a different situation. I reckon about 1/4" of steel plate would do the trick.



     



    Should be good for a standard NATO round  - need a bit more for 7.62 x 51 AP ?


    OMS
     

  • Former Community Member
    0 Former Community Member
    I raised the protective device Andy because I had a distant memory of this cable foil only being required by the BS to pass 160 A, hence limiting it to B32 or C16 circuit-breakers.


    From searching the old forum produces this:

     
    24 April 2015 08:50 AM
    User is offline View Users Profile Send Private Message Print this message




    AJJewsbury


    Posts: 17795

    Joined: 13 August 2003

     

    If the cable was being used for its screening purposes rather than its ADS foil screen nail penetration charateristics, could it be used with type C devices, as the nail test is irrelevant in this case?

    It would be no worse than FP200 type cables that can be used with 'C's, and whose screen is inferior to the 8436 standard??

    Makes sense to me.


    BS8436 is limited to type B devices

    That always felt like a bit of an oversimplification to me - if a B32 is OK, then why not a C16 for instance? - the maximum permitted energy let-through is the same. Or even a fuse if the conditions are right.

    - Andy.




    Who now doubts the necessity of retaining this archive of information?


    Regards


    BOD
  • Former Community Member
    0 Former Community Member
    Well apart from the copy and paste function selectively vertically displaying the post and date info!


    Regards


    BOD

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