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  1. P

    Dodgy PME?

    Not just a rod, but something to deal with the Wylex board! At the least you could add a delay RCD up front so at least you can achieve some disconnection, but really it is a case for a new CU to have some selectivity to keep the lights on if a socket faults, etc.
  2. P

    Max zs mccbs/ACB TNS/TT Systems

    Generally speaking local earthing will rarely be below a couple of ohms, so in parallel with a TN-S sub-ohm value will make little difference. Helps with lightning of course! If your Ze is above the 5s trip impedance then you have a big problem, and an EL kit is one obvious solution. Depending...
  3. P

    Dodgy PME?

    It is possible the old Wylex install relied upon a water pipe bond for earth. Not permitted by the regs for many decades, but still occasionally seen in the wild.
  4. P

    Looking for advice for working with LSZH T&E cable

    Don't forget the Yakety Sax soundtrack to go along with it.
  5. P

    Looking for advice for working with LSZH T&E cable

    It is used just like PVC but you need better strippers to make you life easier. Same for the cable...
  6. P

    Power fluctuations

    We had some UPS with external battery packs at one point and they lacked the ability to tell you if the battery isolator was open or closed. Of course one day power went off and UPS died instantly as a result on no battery! The related MCB tripped / switch off and similar are always a concern...
  7. P

    Max zs mccbs/ACB TNS/TT Systems

    There are some questions about quite what the system is, are some buildings on TT but the incoming supply is TN-S? It is unusual, though occasionally possible, for TT to get a low enough Zs to disconnect on the OCPD side as @davesparks has said, but I suspect on a typical MCCB sized to feed...
  8. P

    Power fluctuations

    Sadly "hope" and "expect" are two very different cases! Not many people apply the resources needed for a high resilience system even though they scream like mad when it goes predictably wrong. And even of those who have put measures in place, quite a few never really test things out. You know...
  9. P

    Will The Terminologies Start Changing?

    That is a very sinister suggestion.
  10. P

    Does replacing a mains switch, which feeds an existing DB require all circuits to be tested on the DB?

    Obviously you need to check the means of earthing, Ze, and polarity no matter what for the EIC. As above, if anything looks dodgy then EICR is a very good suggestion. Even without an EICR being commissioned I would check all of the RCD/RCBO trip-test as an absolute minimum, and check that at...
  11. P

    UK Is this meter and consumer unit location safe and upto spec? (kitchen cabinet, water pipes)

    And this, ladies and gentlemen, illustrates why we should have building regulations like the French where there is a requirement for clear and easy access around the electrical distribution board.
  12. P

    Will The Terminologies Start Changing?

    You can get hermaphroditic connectors in some cases, we used to have a drawer of these: https://en.wikipedia.org/wiki/GR_connector
  13. P

    UK RCD Protecting Distribution Cables on a TT on Industrial Estate

    While it is not an explicit requiem to use a RCD in the TT cases, in most circumstances the guaranteed earth impedance via the rod or steel foundations is not low enough to meet the 1s disconnection needed on any sub-main (distribution) circuits when TT earth is in use. So in practice you will...
  14. P

    UK Electrician looking to move to Australia 2025

    I believe that electricians are a restricted profession in Australia so you must have the required local qualifications and be registered. This goes well beyond part P in the UK, etc, and is more like the need to be Corgi/GasSafe registered by law.
  15. P

    UK MCB's vs Cartridge fuses

    The fuses are part and parcel of the UK domestic plugs so not much choice. For most situations I agree you want a MCB that anyone (within reason) can reset with minimal knowledge, and not a fuse that takes more skill and has a risk of the wrong replacement being used. Debates about I2t levels...
  16. P

    UK MCB's vs Cartridge fuses

    People could, and have, written whole books on the topic of protective devices and achieving selectivity between them. The short version is a 20A MCB will fire in 10ms or so at a current of as little as 60A on its "instant" magnetic trip side, and at 60A a 13A fuse will take between 40ms and...
  17. P

    Bonding within 600mm of gas meter.

    If there is a visible branch and you can't connect before it, you could bond to both pipes that exit the branch to achieve the same electrical goal (i.e. that a poor electrical joint in the pipework does not lead to half the pipework being at a significantly different potential to the MET under...
  18. P

    RCD omission risk assessment

    True. That sort of situation is what I normally deal with and most equipment has multiple earth paths via cables and metal racks, plus I normally bond the rack as well as the supply cable CPC so two paths at least. This might be the reason for the "electrically skilled" aspect not listed, so...
  19. P

    RCD omission risk assessment

    Some of that style of plug can be reversed (the ones with the twin side earths) and others cant (the ones with the earth pin) but typically most now accept either. But I think it is less an issue of the contact and wanting "two pins", more likely the integrity of the CPC connection to the pin...
  20. P

    RCD omission risk assessment

    In this sort of scenario I really doubt the lack of RCD protection for those sockets represents anything more than a C3 code, so no need to replace the DB. If a new TPN DB is needed for other reasons, you might find it is cheaper to change the 3P sockets for ones with the RCD built in than to...

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