Where do the values in Table 7.1 of the OSG come from?
If I look at a 6A Type B Circuit Breaker with 1.5/1.0 mm2 cable, Table 7.1 (p57) gives a max circuit length of 90 metres.
But using Table F6 gives a Volt Drop of 29 mV/A/m for 1.5mm2 cable so 90 metres at 6A would give a volt drop of...