RCD Trips N + E when MCB is down

Discussion in 'Electricians' Talk' started by Victor Lek, Oct 9, 2021.

  1. Victor Lek

    Victor Lek Member

    Hello

    probably a very silly question but, still need an advice from a spark ! Thanks in advanced.

    Today I was changing a socket. The MCB was turned down beforehand and the RCD tripped when Neutral shorted with earth.
    I suppose this is the correct behaviour but I also shorted Live and earth and RCD did not trip. Only tripped when N + E
    Is that normal or should not be the case?
    Again, I’m sorry if this is a very basic one
     
  2. terrymac

    terrymac Screwfix Select

    Normal. Assuming MCB was off when shorting live to earth !
     
  3. Victor Lek

    Victor Lek Member

    Yes. While MCB was off. RCD tripped only when Neutral was shorted with earth but it did not trip when live was shorted with earth. Thanks for confirming this is the expected.
    Cheers
     
  4. seneca

    seneca Screwfix Select

    Completely normal. The rcd didn't trip when you shorted L-E because the mcb was turned off. The neutral remains connected when the mcb is off hence the different response.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice