Two numbers decide whether this test passes: the voltage you apply, and the floor you measure against. Everything else is preparation.
Test voltage is at least twice the nominal voltage, and never below 500 V. The reading must be at least 1,0 MΩ.
8.6.8.1.1: an a.c. or d.c. voltage of at least twice the nominal, minimum 500 V. Take the working voltage as the highest voltage you measured.
Below 1,0 MΩ is not a pass, whatever the tester says or whoever says the install is old. 8.6.8.1.2.
The clause names the equipment that a test voltage will damage. Skipping it is how a sparky buys a dimmer.
8.6.8.1.1(b) and its note. Fuses stay in, switches and breakers closed, loads may be disconnected. Where permanently connected gear would skew or be hurt by the result, the clause allows a single measurement between the live conductors joined together and earth.
8.6.8.1.1 and 8.6.8.1.2. One reading across the whole board can hide a weak section: 8.6.8.1.3 lets you split main supply and sub-boards, but each section still has to make 1,0 MΩ.
PV array DC circuits are not tested to the 1,0 MΩ rule alone. 8.6.8.2 sends you to IEC 62446-1:2018 clause 6.7, and the test has to prove the insulation integrity of the array and its DC wiring.
Practical consequence: test string by string, with the array isolated and the inverter DC side disconnected, on a dry day. A combined array reading tells you almost nothing about which string is leaking.
The CoC test report takes your insulation reading, checks it against 1,0 MΩ, and carries it into a PDF you can send. Plus earth continuity, loop impedance, EL testing, invoices and quotes, all offline.
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