Karl,
Your point is interesting. In the UK Section 607 of BS7671 2001 deals with high protective conductor currents, (often associated with IT equipment such as computers). Where a number of computers are to be connected to a circuit then the cumulative "leakage" current may exceed stipulated upper limits. In this case, in order to protect against possible shock hazards, high integrity earths are required.
There are a number of options but what is being favoured by many specifiers is the adoption of the ring final circuit principle, simply in order to achieve dual return earth paths.
I note your comments with respect to EMI which I ran past a colleague. He acknowledges that building earths should not be run as a ring in general but that the restricted length of a ring final would render it of minimal consequence.
I would appreciate yuor comments.
