Interesting point,David. Would you be kind enough to read this Regulation again? I have just re-read it and it uses Uo, the nominal voltage to earth, not the voltage between lines. I therefore do not think that in a standard three phase and neutral installation in the UK that there is any need to concern ourselves.
Any way,Steve, you should perhaps have a wee look at the Regs in Section 607 relating to protective conductor currents, likely where IT equipment is to be installed. You might also need to consider the csa of your neutral given the likelihood of harmonics.
