I had a call out to look at a hotel kitchens extract fan that had had the supply cable live connection melt, either a loose cable connection or loose grip on the fusecarrier within the transformer type speed controller. No real damage apart from a bit of melted insulation and black copper, was a 4mm on a C20 MCB.
The fan was rated at 8.78 A so I installed a 13A FCU before the speed controller and cleaned up the cables, tested and reconnected. Zs tested out ok for the mcb. Question is when I looked at the mcb it and some of the others were covered in crap, most likely grease as the db is at high level at the end of the canopy covering the cooking line. The DB had a recent EICR sticker, (May 22) but I've not seen the report or know what, if any recommendations were made.
I suggested that the mcbs were changed for new, crabtree 3 phase db so still widely available, but apart from zs and functional switching on the dolly any other way of checking the mcbs are still within spec. I'm a bit concerned about the ambient temp when the kitchen is in full swing but because the extract fan had failed no cooking was going on when I was there.
Relatively clean inside DB but very grubby on the front, not the best fitting cover either.
Would a AFDD have fired off due to the arcing on the connection, staff were saying that they had been unable to run the fan higher than 3, out of 5 speeds because it would stop working but obviously carried on until it broke completely. 
