On Monday, 9 November 2015 11:11:09 UTC, Mike Halmarack wrote:
I was initially set on using a metal lamp holder so as to err on the
heavy duty side but is it this choice that would make 3 core, rather
than 2 core cable necessary?

Probably; there may be double-insulated metal lampholders but you might be better to avoid them for home-made things.


Owain