jan_olieslagers wrote: ....
Still, I think the story about the missing earth being central to what happened is technologically bullshit. If proper earthing fails, people may get nasty electrical shocks, up to and including electrocution. Which we certainly do not want, the earth must be ok. ...
But the earth connection has, as far as I can see, neither the design purpose nor the ability to get rid of excess voltage/power...
You are perfectly correct Jan. Presenting the earth connection as some kind of an overflow path for excessive voltage as if it were water in a tub is nonsense.
I don't know the details of the installation and what happened but I note that reference is made to "400V where 230V was expected".
Well these two numbers are linked in a 3-phase system : when you have 230V between phase and neutral, you have 400V between phases.
There is also another thing that is the type of earthing (or grounding) design. In a 3-phase system, you need a neutral conductor (N) and an earth/ground conductor (PE, for Protective Earth).
This can be achieved by two separate conductors, i.e. a "N" and a "PE". This is called a TN-S design ; T for "terre" (as the IEC/CEI uses both English and French as official communication languages), N for neutral and S for separate).
Or, you can have a TN-C, (C for combined) and then you have only one common conductor, called PEN (Protective Earth & Neutral). Saves on cabling, perfectly legal.
So what happened is probably something around this lack of connection to earth/ground but in the sense that it affects the functioning of a 3-phase distribution system where the neutral is "lost" while you need it.
Well, I realize that by the above I probably have filled the background with so many information that the foreground goes ... underground !
Sorry for that.
Time will tell and hopefully lessons will be learnt.
H.A.