"Adam Funk" wrote in message
...
On 2019-12-05, 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.

...and that's today's holy war started!

I bought lots of GU10 light fittings. Each one was supplied with a spring
connector for the incoming wires, and permanent connections to the fitting.

The spring connectors were just about OK for single twin-and-earth
solid-core wires: the springs retained the wires OK. But some of the
existing fittings that I was replacing had two or even three sets of T&E
going to the screw-terminal junction boxes. The springs were nowhere near
strong enough to retain two or three solid-core wires: at least one wire
would always pull loose.

I quickly learned that the spring connectors were not up to the job, so I
cut each one off and used the existing screw-terminal junction boxes. Much
more secure and certain to clamp all the wires - but I will check them every
few years to make sure that the screws aren't working loose...

So I'm in the screw-is-better-than-spring camp ;-)