This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

How a simple job can go wrong quickly....

Former Community Member
Former Community Member
Not my work before I relate:


Existing 3-ph circuit breaker DB in a shop has a 30 mA 4 pole RCD belatedly fitted in a separate enclosure to provide blanket RCD protection. OK, not ideal.

Electrician asked to install extra 13 A socket-outlet in window during shop hours so padlocks off the circuit's circuit-breaker and proceeds, He lets the circuit neutral and cpc touch when fitting the socket-outlet and out trips the RCD as expected. Resets and shop keeper then announces that the card reader, till, air-con and some lights not working.


All that equipment now duff (technical term!).


For an interesting weekend quiz, what happened?


Without hindsight and the work being done during opening hours, what would you have done differently?


Regards


BOD






Parents
  • I am still pondering the speed at which this happened.


    The live was locked off, the neutral was connected and had a small voltage on it, as did all the neutral conductors downstream of the RCD, enough to push more than 30 mA down to earth when the electrician touched the neutral down to earth by allowing it to touch the CPC or an earthed enclosure bringing the neutral down to near true earth potential.


    The RCD tripped in milliseconds, was the unintentional connection to earth from the neutral still in place when the damage occurred, I assume it would not have been as it would have tied the neutral down to earth stopping the circuits going phase to phase.


    So I assume the unintentional connection to earth from the neutral was flicked in and out in less time than it took for the RCD to trip, not a lot of milliseconds at all.


    Andy Betteridge
Reply
  • I am still pondering the speed at which this happened.


    The live was locked off, the neutral was connected and had a small voltage on it, as did all the neutral conductors downstream of the RCD, enough to push more than 30 mA down to earth when the electrician touched the neutral down to earth by allowing it to touch the CPC or an earthed enclosure bringing the neutral down to near true earth potential.


    The RCD tripped in milliseconds, was the unintentional connection to earth from the neutral still in place when the damage occurred, I assume it would not have been as it would have tied the neutral down to earth stopping the circuits going phase to phase.


    So I assume the unintentional connection to earth from the neutral was flicked in and out in less time than it took for the RCD to trip, not a lot of milliseconds at all.


    Andy Betteridge
Children
No Data