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Shock Likelihood at Switch.

Mornin' All,


I have just inspected and tested a renovated  old flat's wiring. The original lighting wiring in places has no circuit protective conductor. The owner has installed metal plate light switches to two positions with wooden back boxes. At these two positions there is no circuit protective conductor. The flat has a new R.C.B.O. consumer unit and all other wiring is good.


I have recommended that the switches have a C.P.C. installed (difficult and disruptive) or be changed to all insulated types.


Just what is the shock risk at these two switch positions? What is the likelihood of the metal plates becoming live due to a fault? Has anyone every seen a metal plate switch break down so that the plates becomes live?


Thanks,


Z.

  • Former Community Member
    0 Former Community Member
    The result; infinity Ohms. Perfect insulation between the common terminal and the metal plate.


    Quick, get a patent on this perfect tester and insulation..........


    Regards


    BOD
  • Former Community Member
    0 Former Community Member
    Could be worse, BoD - it might have been to infinity and beyond ?


    OMS
  • I was asked to do a HMO EICR in a hurry, because the licence had expired. I failed the installation as unsatisfactory, one of the reasons was a lighting circuit failing an insulation test.


    Having replaced the consumer unit with a new one with RCBOs I identified a metal light fitting worth about fifteen quid that was responsible for the low insulation test result, so I replaced it with a plastic ceiling rose and pendant set.


    Every done, two certificates sent to the customer, the EICR and the EIC each with an invoice detailing the work carried out, including the explanation of why I had took the metal light fitting down and replaced it with a plastic one. I did not throw the metal light fitting away, I labelled it do not use and left it in the house for the customer to dispose of.


    The customer emailed me to say they had paid me and enquired if they could put the old metal light fitting back up now I had finished. Sometimes you just can’t make it up!


    Andy B.

  • Former Community Member
    0 Former Community Member

    OMS:

    Could be worse, BoD - it might have been to infinity and beyond ?


    OMS




    Parallel there OMS where Sid says it, as he takes Buzz out of his room to be blown up!


    Regards


    BOD


     

  • "The customer emailed me to say they had paid me and enquired if they could put the old metal light fitting back up now I had finished. Sometimes you just can’t make it up!"


    That sounds entirely credible to me I`m afraid.


    Yer does yer best but you are still banging yer heed agin a brick wall


  • John Peckham:

    "So Mr Z we have heard from the learned pathologist that the cause of death was electric shock caused by water from a wallpaper steamer dripping in to the light switch have we not? We have also heard from our expert witness Mr P he found that the metal light switch was un-earthed and the special shock protection device known as an RCD was not working. We also heard from Mr P that in his view your report showed the electrical installation was "satisfactory for continued service" as stated in the recognised electrical safety standard was not correct and in his expert view your report should have concluded that the installation was in fact in an un-satisfactory condition for continued service. Mr P also produced as part of his evidence documentary evidence a document from the acknowledge electrical safety body know as Electrical Safety First that clearly indicates that an un-earthed light switch to be potentially dangerous and further more the document says this type of dangerous defect should have lead to the outcome of the report as being un-satisfactory. You said in your evidence in chief that it was your opinion that the electric installation was in satisfactory condition, are you seriously telling this court that you know better than the expert witness and the Electrical Safety First? Or is the case that you took money from the landlord, who needed a satisfactory report, and getting payment for your services would have been more difficult so you gilded the lily to please him? 


    I sat in the well of a court in the Emma Shaw case where the electricians mate confessed when challenged about his entries on a test certificate said "I would not have done it if I had known" . 




    There has been no death. The wall will not be steam stripped of wall paper as it has recently been painted with new emulsion paint.


    Z.

  • Former Community Member
    0 Former Community Member
    The wall will not be steam stripped of wall paper as it has recently been painted with new emulsion paint.


    Another patent on the crystal ball?


    Regards


    BOD
  • John, in the unfortunate Emma Shaw case I believe that no R.C.D. circuit protection existed. In my case the lighting circuit is protected by a 6A R.C.B.O.

    https://www2.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=57216


    Z.
  • Former Community Member
    0 Former Community Member
     In my case the lighting circuit is protected by a 6A R.C.B.O.


    And the failure rate of RCDs compared to circuit-breakers is?


    Regards


    BOD
  • Interestingly, in the ROI, as I may have mentioned before, had the intrepid Zoomup faced the same situation, he would have had 4 code choices, two of which could be discounted. Code 1 requires urgent attention or Code 2 requires improvement. No declaration on whether the installation is satisfactory or unsatisfactory is required on the report. That firmly shifts the onus on to the recipient to decide what action is to be taken. In Zooms case, I suspect he would have went with Code 2 which is a fairly unambiguous message for the owner of the flat. Then again, perhaps the Code 4 “does not comply with the current national rules for electrical installations” which is further expanded with “this does not necessarily imply that the electrical installation inspected is unsafe”, might have fitted some aspects of Zooms argument. Anyway, I am simply musing but I do like Zoomup and if he needs support I Would offer to grip the rail along with him. I could at least tell the beak that he did sterling work in uncovering the defect in the first place, something that perhaps others might have missed!