Following a trip to a local UPS delivery point on my way home today, I am now in posession of my shiny new copy of IET Guidance Note 3 - Inspection & Testing (10th Edition).
On Page 73 under Figure 2.23 in connection with insulation resistance testing it states:
'The insulation resistance readings obtained should be not less than the minimum values referred to in Table 2.9'
However, on turning to Table 2.9 on Page 67, it appears to be concerned with the variation in resistance readings when testing ring final circuits where the line and circuit protective conductors have different cross-sectional areas.
It would appear that the statement on Page 73 should actually refer to Table 2.10 on Page 70 which is concerned with minimum values of insulation resistance?
Either that, or it is far too late in the evening to be considering such matters and I am missing something fundamental . . . 
