I always switch off the relevant mcb when I am working on a circuit,quote]
Have you heard of a shared (or is it borrowed) neautral? I'm no spark, but IIRC they can be a hazard. Just switching off one mcb may not protect you. Please correct me someone if that is not true.
I think you ought to stop what you are doing, or up your insurance. I know a little, but also know that is probably worse than nowt as it can make you over-confident.
Just my 2p