And remember that RCDs or GFCIs are not the panacea they may seem like at first. All it takes is an unreferenced secondary and voila, ground faults are invisible.
Can you explain what you mean by unreferenced secondary in this context?
a galvanically isolated transformer, i.e. a voltage that is not referenced to ground, meaning an RCD/GFCI will not be able to trigger if you touch it and it starts zapping you