Why would this be? And I've got the 20 char thing too??

[Leader]

I'm confused as to why the below happened.

1) isolated downstairs lighting circuit, kitchen light still works

2) isolated kitchen light and provided an earth for the diy metal light switch (after seeing the lounge switch didn't have one either)

3) after sorting all switches energised the circuit, MCB tripped. When MCB back on the kitchen light wouldn't switch OFF. Traced fault to loose line in kitchen switch. Sorted and all now fine.

 

[SparkyChick]

I'm not sure what you're asking... without being there and seeing it, it's impossible to say what may have caused it. Just sounds like a very dodgy install.

 

[Richard Burns]

It sounds like the kitchen light switch temporarily welded itself on, possibly with the arc from the fault current flowing when the MCB tripped. Though it is not clear which circuit the kitchen light is on or which MCB tripped.

 

[Leader]

Well it tripped the downstairs lighting circuit. Which is why it's odd the light stayed on when that circuit was isolated.

 

[Leader]

It does seem a bit of a dodgy install @SparkyChick, and also pretty old.

 

[SparkyChick]

I've been dealing with an EICR for LABC regularisation the last few days (some pics to be posted) and one of the things I checked, based on the fact I had CPCs connected on different circuits within the installation was actually systematically turn on one circuit at a time and check for the presence of supply at the load terminal of each circuit just to make sure I had no interconnected circuits. Also did IR between many of them to double check.

Could be a mixup like that.

 

[Octopus]

Could it just be the fuseboard is labelled incorrectly?

 

[SparkyChick]

^^^ LIKE ^^^

 

[hightower]

Circuit fed from two breakers is my guess, i.e. A cross connection somewhere

 

[Leader]

I initially thought it must be interconnected circuits but the fact it then blew the correct MCB made me think otherwise??
Couldn't be incorrectly labelled as it tripped correct MCB.
@hightower, that could explain it as could Richard's suggestion.