Hello all, Been to look at a fault today which consisted of the lighting circuit tripping the mcb. When looking into it further no obvious fault became apparent. When I took a look at the d/b I found some scorch marks and melting of the plastic on the neutral rod from the load side of the main switch. The main switch is a 30ma RCD.Also when looking at one if the loops into a ceiling Rose I could see the start of some heat damage on the neutral there as well.I spent all day investigating all my dead test came back okay, ze values and RCD times okay. I do not think it is overload issue as it is a basement flat not many circuits, no major loads. The only other advice they gave was that they sometimes used the shower and the trip went and the could smell that nasty hot plastic smell.I have let it safe tonight but going back tomorrow hoping that the occupant in the flat above accommodating to let me investigate through her floor. Has anyone had a similar problem or any suggestions why the scor h marks. I have checked the terminations in the board and they Are okay , neutral nice and tight .Any input would be greatly appreciated