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IET announces new amendment to BS 7671 (IET Wiring Regulations)

Lisa Miles
Hi all


Just read about this in the latest edition of Wiring Matters Magazine and thought it may be of interest!
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    In English then

    SRCDs are intended for use in circuits where the fault protection and additional protection an RCD are already assured upstream upstream of the SRCD .




    so, pointless, unless you require to play the chance of failure game, and cascade 2  devices with poor failure rates, to have a system over all with a reasonable one.

    So if say the change of wither the 1st RCD or the second failing to trip is perhaps 5%, the chance of both failing, so long as the failure mechanisms are independent is 0.25%.

    I suspect this is not the intention.


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    BS 7288: 2016 says.


    " SRCDS are only intended to supplementary protection downstream of the SRCD. SRCDs are intended for use in circuits where the fault protection and additional protection are already assured upstream upstream of the SRCD".


    So these devices can no longer be used for additional protection. I assume this is why the do not appear in Appendix 1 of BS 7671 or in the body of the standard.


    I do not know if SRCDs made to the previous standard, BS 7288: 2009, are suitable for additional protection as they were of a different construction or it was discovered that all types are unsuitable? 


    So if you discovered an SRCD installed on an installation for additional protection or fault protection on a Periodic Inspection they would be a C2?


    I think this is the issue Graham Kenyon was referring to on the earlier thread.
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    I clicked the link Mike put above then kept going until I got to the BSI login for the drafts, my Ipad remembered my login details from when I viewed the draft 18th document and entered them for me and I was in. 


    Andy Betteridge
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    Chris


    Thanks for the reference I had not read that thread.


    Graham Kenyon was pointing out the changes to BS 7288 that now says that SRCDs cannot be used for addition protection and says that they can only be used if there is already upstream additional protection. I need to check but I think BS 7288 references disappeared from the 17TH and does not appear in the 18th. Hence I would be interested in other people's views?


    I will cut and paste the actual words from BS 7288 when next in front of my desk top.


    Andy


    Where did you find that reference to JPEL clarifying the use of devices to BS 7288?
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    I suspect the "updates" link should have been: https://electrical.theiet.org/bs-7671/updates/, but nothing about this there yet.

      - Andy.
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    John Peckham:

    I would be interested to see forum members comments on the most recent edition of BS 7288? I may be coming to the wrong conclusion but it would appear to me that RCD sockets and SFCU have been rendered pointless. 


    Any views?




    Already expressed here on 11 Aug (page 2).


    Not entirely pointless because I think that it would be reasonable to replace an ordinary socket with one where the householder does not want to have the circuit, or even whole CU upgraded. Let's not forget that there is no obligation to update an installation. A new circuit is a different matter.

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    I would be interested to see forum members comments on the most recent edition of BS 7288? I may be coming to the wrong conclusion but it would appear to me that RCD sockets and SFCU have been rendered pointless. 


    Any views?
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    does not work as expected. So actually we have no idea what is being considered from this article.


    more useful here
    bsi website



    That seems to be a different piece of work - the BSI web site provides a .docx which lists a whole lot of proposed work including Low voltage generating sets, Construction and demolition sites, Exhibitions, DC power distribution over information technology cable infrastructure, DC power supply system in the data centre, Energy Efficiency and Smart Low-Voltage electrical installations as well as EVSE - with a DPC due September next year and publication April 2022.


      - Andy.
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    There would be something amiss if you didn't foresee debates in this forum. ?


    As I understand it, the authorities have accepted that there are shortcomings in the 18th Ed, and manufacturers have moved forwards. We are due a DPC next month, but until that is released, it is difficult to make further comment.
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    “Additional change agreed following April 2019 meeting to include reference to BS 7288 for SRCD and FCURCD in clauses 531.3.4.1 & 531.3.4.2”


    Hopefully the change will resolve most of, and preferably all of, the possible issues of using this type of RCD within an electrical installation.


    Though I still foresee some debates of this forum.


    Andy Betteridge

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