Christian McArdle wrote:

Personally, I would regard the junction box as too far from the light, so
unacceptable unless the CPC was 4mm, which is VERY unlikely. However, it
would be acceptable if the CPC was protected, such as being in a metallic
conduit, and otherwise met supplementary bonding regulations for minimum
size.

Provided that the run from the JB to the light is fairly direct and is
in T&E cable I don't see why bonding to the CPC in the JB wouldn't be
OK. A CPC in a sheathed cable is deemed to be protected for this
purpose [see Regs. 547-03-01 to -03].

Bonding to the lighting circuit's CPC is not required if the light and
any other accessories on the circuit (e.g. shaver point, fan) are
outside the Zones.

--
Andy