Unexpected Tripped Breaker

[recycleit]

hello and thanks for your previous help

last night i had switched off the power to the socket in the loft to remove some redundant wiring which had been left live and taped up when the main breaker on CU tripped.

the wire came from a fused switch box which is also connected to an aerial amp, so my theory is some power left in that went down the earth and tripped it.

is this likely in your opinions?

 

[breezer]

its not the main breaker its probably the RCD have a look again.

neutral to earth short is supposed to do this

 

[Lectrician]

The RCD tripped? (as opposed to an MCB).

You isolated this circuit by turning off an MCB, which are predominantly single pole in most applications. This left the neutral of the circuit connected. A neutral to earth fault will cause operation of an RCD due to circulating currents on the other circuits protected by this RCD. You effectively give the current from the other circuits a second path to flow down, and some did.....atleast 30mA worth (the trip current of your RCD).

I guess you either chopped the cable, or inadvertantly caused the neutral and earth to short, or the neutral to come into contact with something else earthed.

Easily done, and expected.

 

[recycleit]

Thanks

That explains it.

View media item 1046
Hope picture works as it shows the CU and RCD switch

Thanks again

(Image fixed - Mod9)