"patrick j" wrote in message
. com...
Hello

Over the Christmas period I replaced all the pendant lights in my
house. They
all had shades I didn't like and those shades were screwed in to a
lamp
holder which wouldn't take the replacement shades, so I changed the
lamp
holders of course. These new lamp holders are pretty standard
"British" ones
which have been used here in the UK for many years.

In the past when I've been putting in any new electrical fitting I've
always
put some solder on the exposed cable which I'm going to screw into the
fitting. I've done this when wiring plugs for example.

However with these MK lamp holders it says in the instructions:

Carefully strip the inner cable insulation to expose 10mm of
conductor. If using an existing cable with soldered ends,
they should be trimmed back and re-stripped to expose new
clean conductor. On no account should soldered ends enter
the terminals.

So it looks like MK believe that soldered cable ends are a bad thing
and of
course I did not put solder on the cable ends.

I am sure MK are quite right in their advice but I would be grateful
if
someone would explain to me why soldered cable ends are a bad thing.

--
Patrick

At a guess it's because with soldered ends don't 'give' when you tighten
the screw.
1 - you could end up with contact just along the two opposite sides of
the solid cable, rather than letting the cable compress to give a larger
area of contact.

2- Also if the soldered end was roughly elliptical in section the same
lack of 'give' could allow you to tighten the screw onto the wider axis
and it would seem to be firm; but if the cable rotates it could come
loose giving arcing.