Recent content by Guineafowl

  1. G

    When 50,000 volts go through a wire at 5,000,000 FPS - The Slow Mo Guy

    What I said seemed to be the conclusion of Veritasium’s experiment? Time to first current pulse in the bulb was 1m/c seconds, determined by the 1 m straight-line distance from switch to bulb, rather than the 1 second you’d expect as the wires were 1c metres long, assuming a velocity factor of 1.
  2. G

    When 50,000 volts go through a wire at 5,000,000 FPS - The Slow Mo Guy

    A ‘negative’ wavefront? Does an opposite wavefront travel the other way around the circuit? I did see those, and the responses from other channels. Interesting, but no substitute for understanding at the deepest levels, of course. More on the level of Feynman’s ‘fun to imagine’ descriptions. A...
  3. G

    When 50,000 volts go through a wire at 5,000,000 FPS - The Slow Mo Guy

    The terminals of whatever power supply they have?
  4. G

    When 50,000 volts go through a wire at 5,000,000 FPS - The Slow Mo Guy

    Could it be said that the connecting wires have some velocity factor, eg 0.7, and the electric (electromagnetic?) wavefront travels at 0.7c around the outside of the wire, which acts as a sort of ‘waveguide’? Would it also help to think of current not as electrons drifting along like little...
  5. G

    Following up on the recent thread about Earth Resistance measurements

    The PV installers wouldn’t have seen a problem - 130Ω is within spec for TT. Don’t forget the RCD requirement. I can’t explain why you’re not TN-S - perhaps the earth loop impedance (as it’s called, although I was scoffed at on here for doing so!) was above the 0.8Ω max due to poor connections...
  6. G

    Following up on the recent thread about Earth Resistance measurements

    Unlikely. - Service head belongs to your DNO. - Meter belongs to your energy company. - Anything after that belongs to you, and you or your electrician can play with it. Secondly, going from TT to TN-S, you are changing from customer-supplied earth, to one supplied by the DNO and which they...
  7. G

    Following up on the recent thread about Earth Resistance measurements

    I’m not sure what you mean by this - in the common TN-C-S system they are linked. Unless you mean YOU are forbidden from doing it, which would be true - the service head belongs to your DNO (Distribution Network Operator), and changing the earthing system would require permission from them and a...
  8. G

    Following up on the recent thread about Earth Resistance measurements

    Ok. It’s hard without being there or seeing pictures, that’s all. Does it dive into the wall, where do you lose sight of it? In any case, if it doesn’t connect to the service head (earthing types 2 and 3 above), then you have TT earthing. If you can’t find the rod, next stage is a live loop...
  9. G

    Following up on the recent thread about Earth Resistance measurements

    I’d have to add (see post #11) that this is not the case for TT and TN-S installations.
  10. G

    Following up on the recent thread about Earth Resistance measurements

    One further thought, @sophiecentaur , is that your PV installation should have involved some basic electrical tests on the existing supply. Did the PO leave behind some paperwork with regard to this? It should be in the form of an electrical test certificate, detailing earthing system and Ze...
  11. G

    Following up on the recent thread about Earth Resistance measurements

    Yes, in all three systems the neutral/PEN is earthed at the transformer end.
  12. G

    Following up on the recent thread about Earth Resistance measurements

    I’d say you might be on a TT or TN-C-S system (see below), so in that case, no, but we can’t be sure yet. I also can’t yet explain your high k reading between supply cable armour and your earth, except to suggest inadequate earthing at your end. - Can you post a pic of the service head? -...
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    Following up on the recent thread about Earth Resistance measurements

    Here’s a interesting document about socket testers: https://www.electricalsafetyfirst.org.uk/media/1205/best-practice-guide-8-issue-2.pdf It seems that, if anything, they might a little generous with the ‘earth ok’ light.
  14. G

    Following up on the recent thread about Earth Resistance measurements

    That sounds like TN-S earthing. Max external earth fault loop impedance reading (Ze) is 0.8##\Omega##. I’d certainly call someone in to verify your new house’s earthing system. If you get only L and N, you’d normally need your own earth rod, so-called TT earthing. Max Ze is technically around...
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