...
We have an earth-shift of approximately 60-90V that cannot be avoided in this setup. Touching earth is not dangerous but also not nice. Actually it might also be the case that one of the cable drums has a disconnected earth (such a high earth shift is unlikely). This is actually dangerous as a device with an insulation error will put full 230V on earth/case of all metal devices. The RCD in Reiks fuse box gives a high level of protection, so it is nothing to be really worried about but also should be kept in mind.
Also, the RCD is more likely to blow than under normal circumstances. Unfortunately, there is no way of prevention (and putting a second fusebox in our house would not help as it is not possible to reliably only blow our second fuse and not the first one).
...