Search results

  1. E

    Lack of supplementary bonding - what’s the danger ?

    Exactly that- you can see on your picture the bond is forming just a lower, very slightly lower resistance path than the strip of copper on the met - can you not see that ?
  2. E

    Lack of supplementary bonding - what’s the danger ?

    Yes I get that my whole point was around the benefit it practice of what will already be a very low potential difference if bonding and CPCs are correctly connected. I’m going to measure this in my 2nd floor ensuite today out of interest (no supp bond in place, copper pipe work )
  3. E

    Lack of supplementary bonding - what’s the danger ?

    That’s assuming the bond is made at the tap itself other than in reality some other point in the pipe work
  4. E

    Lack of supplementary bonding - what’s the danger ?

    Still thinking about this !!! You have conveniently drawn the supp. bond at the point of touch, let’s say the tap. If the supp. bond was connected at say the floor level, electrically this is no different to without supp. bonding in place in your picture other than a negligible additional...
  5. E

    Lack of supplementary bonding - what’s the danger ?

    No circuits that supply a bathroom are permitting have 5s disconnection time
  6. E

    Lack of supplementary bonding - what’s the danger ?

    Won’t an mcb work to limit the same duration - I.e operate within 0.4 seconds in the same scenario?
  7. E

    Lack of supplementary bonding - what’s the danger ?

    “As I've said, the only thing that will remove that risk is supplementary bonding within the location.” Johnw2 your comments above - so anRCD will not ? Why ?
  8. E

    Lack of supplementary bonding - what’s the danger ?

    Yes penny has dropped . The supp bond closes the loop in the earthing arrangement. I see it now. Thanks for being patient. How is an RCD going to help in that scenario? (Without supp bonding) It isn’t is it ? Which begs the question why is it (sup. Bonding) permitted to be omitted if it’s RCD...
  9. E

    Lack of supplementary bonding - what’s the danger ?

    I’m talking without supp. bonding. The 2 points A and B are joined by a low resistance path formed by the ECP, pipework and bonding
  10. E

    Lack of supplementary bonding - what’s the danger ?

    Let me put it another way. The supp. Bond cable is to make the resistance between the things you can touch that are extraneous as low as possible. A copper pipe in the bathroom that is connected to the MET by a 10mm2 wire is likely to be in the 0.05 ohm bracket, is it not ?
  11. E

    Lack of supplementary bonding - what’s the danger ?

    Fair enough, but I thought you were questioning the value of supplementary bonding. You now seem to be agreeing that, in practice, it will always limit touch voltages to 'very safe levels'? No - I’m saying that without supplementary bonding the resistance of the ECP and the CPC from the...
  12. E

    Lack of supplementary bonding - what’s the danger ?

    So you are now agreeing it wouldn’t be 144V ??
  13. E

    Lack of supplementary bonding - what’s the danger ?

    I agree with all of the above, I used 0.25ohm to show how big the resistance would need to be before a safe level of 50V was exceeded even with a large fault current and ignoring parallel path of the ECP. Back to my initial post - supplementary bonding where main bonding is sound is like putting...
  14. E

    Lack of supplementary bonding - what’s the danger ?

    lol
  15. E

    Lack of supplementary bonding - what’s the danger ?

    Oh yes, sure you were my whole original post was around in a dwelling, the differences would be negligible due to relatively short lengths of cpc and parallel paths with the ECPs and main bonding for supplementary bonding to make a difference
  16. E

    Lack of supplementary bonding - what’s the danger ?

    What’s your calculation to achieve 144V ? I assume 240/1.667 ? In the top picture, from another forum poster: If the resistance between point A and B is 0.25ohm then with a fault current of 200 A causing instantaneous trip of the OPCD then the voltage would be 50V ?
  17. E

    Lack of supplementary bonding - what’s the danger ?

    Depends on the magnitude of the fault current and the resistance of the cpc between A and the MET and R1 ? (Assuming negligible resistance of the supp bond)
  18. E

    Lack of supplementary bonding - what’s the danger ?

    Well you must like the look of green and yellow cable !
  19. E

    Lack of supplementary bonding - what’s the danger ?

    Because my question is, I’d like to know a scenario where touch voltage is going to exceed let’s say 50 V main bonding is in place and all circuits in the location have a CPC
  20. E

    Lack of supplementary bonding - what’s the danger ?

    By connecting metal items that do not form part of the electrical installation or are not extraneous conductive parts to earth your are introducing voltage potentials under non fault conditions. Woukd you/have you also bonded your window frames , kitchen sink , metal fire surround etc etc ?
Back
Top