also on page 279

8.7.8.2 The insulation resistance, measured as follows, shall be at least
1,0 MΩ:
a) to measure the insulation resistance to earth, apply the test voltage
between the earth continuity conductor and the whole system of live
conductors, or any section of it; and
b) to measure the insulation resistance between the conductors, apply
the test voltage
1) between the phase conductors, and, when relevant,
2) between the phase conductors and the neutral conductor.
8.7.8.3 When there are sub-distribution boards and the total insulation
resistance is less than 1,0 MΩ, the insulation-resistance test may be
carried out by
a) isolating and testing the wiring between the main supply and the subdistribution
boards, and
b) testing, as a separate section, each sub-distribution board connected
to all the circuits that it feeds, but the insulation resistance in each
section shall be at least 1,0 MΩ.


Now you see thats what i also thought until i read the new amendment no.8 carefully.

you will find this note...

8.7.8 Insulation resistance
NOTE 1 Before power is connected to any new or altered circuit, the test for
insulation resistance should be carried out to ensure there is no short-circuit or
high impedance faults in the installation, and that it is safe to energize. Amdt 8

NOTE 2 In the case of existing installations where the power may not be switched
off from certain circuits in order to carry out this test, the fact that the circuits are
subject to the supply voltage can be regarded as evident that the insulation
resistance is compliant. Amdt