Some is, some isnt. I suspect someone laid the insulation after the electricians had finished wedging wires tight into back boxes! When I have more time i will expose it....63A
Not under insulation is it? That can drastically affect the current carrying capacity of the cable.
Its thick cable - will onlu just fit in the switch connectors really. Just measured and its 7 strands of copper just over 1mm diameter. Cables about 6mm diameter with the insulation and 5mm diameter with the strands twisted without insulation.

been replacing hundreds of light fittings in offices and a school and loads more in peoples houses for the last 55 years
shoulda got a job in some works easier with a good pension