Welcome to the mad house.
You mention Belgium and France as having predominantly TT systems, what type do you have in the VERY WEST OF GERMANY? And where is the very West of Germany? Do you have Rcd's fitted as standard by the PoCo?
This thing about it being normal to have a current passing to earth still seems alien to me. Yes,if you have all the equipment to monitor it and logicaly deduce that it's O.K. fine. But so many people buy second and third hand equipment nowerdays nad it gets connected. For Instance the other day I did an inspection on a property; testing revealed that the cooker circuit did not have an earth connection to it,15 years it had been like that. The cooker had been changed once,re-conected by a well known supply house,it turned out to be an earth connection broken off for 15 years. If the cooker had developed a fault, who knows!!! If it trips out it needs proper investigation and thats the end of it as far as I am concerned. regards aland