MCB Tripping

Discussion in 'Electricians' Talk' started by PHILPH, Jun 4, 2021.


    PHILPH Member


    My toaster is obviously knackered as it's tripped the fusebox, however it's knocked the main fuse box switch?

    I'm a non electrician, however I thought it would just trip the MCB that the circuit that the socket was on in the kitchen and leave the electric on for everything else?

    Would that be right or could there be another problem lurking somewhere else?
  2. Tony Goddard

    Tony Goddard Screwfix Select

    The main switch is probably an RCD (you can tell this because if it is it will have a button, labelled test, it may have RCD or RCCB written on it) The RCD detects the leakage of current to earth, so if you toaster has a fault to earth it can quite easily knock out both the MCB and RCD.

    This demonstrates your fuse box (consumer unit) is doing it's job of preventing the risk of a fire or a shock.

    Time for a new toaster.
  3. IW guy

    IW guy New Member

    Probably not. The most common reason for toasters tripping an RCD is burnt toast crumbs bridging the element to the case. Unplug it, take it outside, pull out the crumb tray and clean it, then turn the toaster over and give it a good shake. Inspect the toast slots for burnt crumbs on the element and dislodge them carefully.

    PHILPH Member


    There’s no test button on the main switch however lm happy if it’s just a toaster to replace but I will check the crumb tray as suggested.

    Many thanks for your replies.
  5. The Happy Builder

    The Happy Builder Screwfix Select

    Then how can it been knocked off?
  6. Dan Greenslade

    Dan Greenslade Active Member

    Take a picture of your CU if you can please and tell us which switch had tripped..
  7. Tony Goddard

    Tony Goddard Screwfix Select

    The main switch must be an RCD or a circuit breaker as clearly a main switch won't turn itself off - agree with Happy & Dan that a picture will assist.
    On some RCDs the test button is not screamingly obvious, once upon a time they were generally a round or square yellow button with TEST written by it, now they can be small, blue or grey, oval or shaped in some way and can just look like a part of the design of the thing.

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