Wow, thats quick service, posting the problem at 3.12pm and the spark has been round and identified the problem by 4.41pm 
SS and TTC, I wonder if a bit of rewiring to get rid of the borrowed neutral has caused the spark on the job to fit RCDs to cover the new work, so meaning new board?
(The OP did say nothing had changed for years at his mum's, so I'd guess that there is probably an old 3036 board in place)
SS and TTC, I wonder if a bit of rewiring to get rid of the borrowed neutral has caused the spark on the job to fit RCDs to cover the new work, so meaning new board?
(The OP did say nothing had changed for years at his mum's, so I'd guess that there is probably an old 3036 board in place)
