Puzzled

[PrenticeBoyofDerry]

I am going to check today, as it is sometime since I originally did work in property, returned this week as the kitchen fitter has been. I was reminded of the issue on return, thinking it would be easily solved.
But I am sure I tested voltage prior to replacing socket plate, I all ways do! But will double check that i was not having an off/on day!

 

[PrenticeBoyofDerry]

After revisiting the property, and confirming continuity, polarity, voltage values, Zs and RCD tripping.
I then checked the breaker, and it seem a faulty breaker on he kitchen radial was a factor.
As this breaker was not opening, still strange though! I did try all breakers and they did power down circuit/parts of circuits.
As the socket under question was not worked on until recently and after the new kitchen was fitted. I can only assume that the MCB has become faulty since I first worked on the circuit and was asked to replace the face plate on this particular socket outlet.
But still puzzled why, when I removed the live busbar from iso and MCBs, the socket came live when main RCD isolator was closed and then powered down when opened?

 

[sparkwright]

Any water finding it's way into the CU?

 

[deadshort]

To my mind the only logical way for that to happen would be reverse polarity at the CU, but you checked that.

DS

 

[sparkwright]

Yes, I keep thnking a polarity issue myself.

 

[ban-all-sheds]

Reverse polarity might mean that a magic wand lights up when the breaker is off, but no matter how many very good reasons there are why we don't allow SP switches in the neutral, if a switch in the neutral is opened the socket(s) will not power appliances any more.