According to Steve Barker :
So,,, this aledged wire that is 150 degrees? Why is it hot and why hasn't
it tripped a breaker? And why hasn't the insulation melted off of it in the
exposed fixtures the OP has shown?

Cable defect or punctured with a screw which causes an intermittent
poor conductance short - not enough to blow the breaker, but enough
to heat things up. Could be load related. Could be something
really stupid like an "in-air" splice without proper connectors (cue
other thread). Could be that some dweeb wired it with lamp cord
because he ran out of proper stuff (cue a different thread).

If every "overheat" caused a wholesale fire, there'd be vastly more
houses going up in smoke.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.