On Thursday, 5 December 2019 12:07:51 UTC, Pancho wrote:
On 05/12/2019 12:02, Jethro_uk wrote:


Repeated mechanical shock of heating/cooling (exacerbated by arcing if
the wires were loose to start with) leading to the screw slowly following
the thread ?

Is that why, spring, wago style connectors are mandated for inaccessible
junctions.

Yes, surely you shouldn't be using spring connectors in autumn.