Special non rcd socket for pat testing

Discussion in 'Electricians' Talk' started by tina lucinda lane, Jan 13, 2021.

  1. tina lucinda lane

    tina lucinda lane Screwfix Select

    Hi the charity shop I work for may soon be getting a 3 phase rcd system installed (either an incomer or 3 separate units) I want to know can I have a socket (radial final) fitted run from supply to location supplied only from a incomer and mcb as a single radial with no rcd specify for test purposes as testing rcd extension leads (either socket or plug) or plug through rcds using appropriate rcd tester (which I have got) to test trip times with out affecting the rest of the shop (appropriately labelled of course)
     
  2. The Happy Builder

    The Happy Builder Screwfix Select

    You need to make yourself a testing adapter with a plug, around 4” of flex and a trailing socket to keep with your PAT testing gear.

    Make the lead up with the earth wire in the plug connected into the neutral in the plug, then when you test the plug in RCD the fault current to earth runs back through the installation neutral through the installation RCDs without tripping it.

    Label the lead for testing purposes only and keep it secured with the PAT tester. As the lead is only around 4” (100 mm) long it’s not much use for anything else anyway.

    There are other ways of doing this, but when working with leads that all have 13 amp plugs on them this is the easiest.

    Now for the risk assessment, although the neutral should be at near zero volts it is a live conductor within the installation, so technically you are connecting the earth of the item under test to a live conductor albeit one that should not have significant voltage on it. So be careful about what you use it to test and only do it safely on the bench.
     
  3. tina lucinda lane

    tina lucinda lane Screwfix Select

    OK thanks that's quite an option the installation uses the suppliers earth on a underground supply (ie the armor jacket as earth)
     
  4. Teki

    Teki Screwfix Select

    Comlec likes this.
  5. tina lucinda lane

    tina lucinda lane Screwfix Select

  6. Bazza

    Bazza Screwfix Select

  7. Teki

    Teki Screwfix Select

    Yeah it is quite expensive, perhaps search for deals online or second-hand ones.
     
  8. Bogle Crag

    Bogle Crag Screwfix Select

    It claims to isolate from the supply but says its not a transformer, probably some electronic wizardry
     
  9. The Happy Builder

    The Happy Builder Screwfix Select

    I think basically it is.
     
  10. The Happy Builder

    The Happy Builder Screwfix Select

    All you need to do is send the earth current from your RCD tester back through the neutral of the installation RCD, so there isn’t an imbalance between live and neutral at the installation RCD.

    There’s a few ways of doing it.
     
    tina lucinda lane likes this.
  11. tina lucinda lane

    tina lucinda lane Screwfix Select

    Thanks for the advice I may speak to the spark doing the rcd retro fit and ask if a radial socket for test use would be an option could even be installed in the electrical cupboard before being plug extended to my work desk area (one in cupboard labelled non rcd socket not to be used to supply outdoor equipment or suchlike, as fitted for installation of a temporary meter man's light, and at the work bench end labeled no rcd protection for test use only and similar label at the plug end as to where it goes like I say I will ask them about it as an option)
     
  12. FlyByNight

    FlyByNight Well-Known Member

    Have a single radial that terminates in an MK K1246 twin socket or K1257 single. That could be fitted on your workbench. Then have, under YOUR control, a lead with an MK 647 plug to trailing socket.

    Plus ALL of the warning signs including ones that say "un-approved/unsupervised use of this supply may present a danger to life"
     
    jayktee likes this.
  13. tina lucinda lane

    tina lucinda lane Screwfix Select

    Perfect that would work fantastic does anyone else remember having a small 5amp socket next to a main fuse but linked off the supply side of the main fuse labelled for temporary inspection lamp only stayed in an old cottage in England that had this wish I'd taken a photo of it but was before phone cameras or even mobile phones
     
  14. FlyByNight

    FlyByNight Well-Known Member

    Or there are versions with Red Rockers or Red Face Plate which will serve to further differentiate.
    https://www.mkelectric.com/en-ar/Pr...cketoutlets/Nonstandard/Pages/K1246D1WHI.aspx
     
  15. The Happy Builder

    The Happy Builder Screwfix Select

    IF, and it’s a very big IF, you were to have a dedicated socket without 30 mA RCD protection for testing there would be no justification for it being a double socket to allow two items to be connected at the same time.
     
  16. MGW

    MGW Screwfix Select

    I used a 230 to 110 volt transformer and a 110 to 230 volt transformer, simply as I had them for other uses.
     
  17. Comlec

    Comlec Screwfix Select

  18. Teki

    Teki Screwfix Select

    That would work or just an isolation transformer. You can often find used ones fairly cheap.
     
  19. FlyByNight

    FlyByNight Well-Known Member

  20. The Happy Builder

    The Happy Builder Screwfix Select

    What’s the earthing arrangement on an isolation transformer and how do you connect the RCD under test to the transformer to get the earth connection?
     

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