Earlier today I turned off the power to consumer unit as I wanted to change a light switch. After changing the switch I reactivated the consumer unit main 100amp breaker, at which point the MCB for the Ring Final at the back of the house, on a completely different circuit activated and turned off. The MCB was completely unconnected with the light switch I changed and reactivated no issues whatsoever. I have an insulation and continunity tester from a former life, albeit it is slightly old now, which I have used to test the circuit with good readings across the board. There is no regular tripping in the house and in the 6 years ive lived here never had a MCB tripping episode. There's been no recent rain, albeit I'd expect that the trip the RCD not the MCB and no recent DIY that would cause an issue.
Is there a simple explanation as to why the MCB activated when power was reapplied when I reactivated the main 100A breaker?
Is there a simple explanation as to why the MCB activated when power was reapplied when I reactivated the main 100A breaker?