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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
  • 0

    perspicacious:

    Not my work before I relate:


    Existing 3-ph circuit breaker DB in a shop has a 30 mA 4 pole RCD 






    Mike has it. The neutral was disconnected before the phases when the R.C.D. tripped off and the loads were subjected to 400 Volts. Even though the loads would be connected like a star connected motor, the star point being  at the neutral bar,  the equipment could have been damaged by a transient over Voltage if the N. of the R.C.D. opened before the L1, L2 and L3 contacts.



    Z.



     




     

Reply
  • 0

    perspicacious:

    Not my work before I relate:


    Existing 3-ph circuit breaker DB in a shop has a 30 mA 4 pole RCD 






    Mike has it. The neutral was disconnected before the phases when the R.C.D. tripped off and the loads were subjected to 400 Volts. Even though the loads would be connected like a star connected motor, the star point being  at the neutral bar,  the equipment could have been damaged by a transient over Voltage if the N. of the R.C.D. opened before the L1, L2 and L3 contacts.



    Z.



     




     

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