In article , Brian
writes

With that in mind, this is what I did:

- twisted the cables together using pliers
- tinned the soldering iron
- heated the joint and flowed solder onto it
Sounds good.

I used a gas-powered soldering iron because, obviously, the power was turned
off.
Do you only have one ring?, handy to have 2 for just such an occasion as
this, also this would be on of the few acceptable situations to use an
electric iron wired up to a lighting circuit adaptor.

The joints I made seemed strong but didn't occur in just a few seconds - in
some cases I had to heat the joint maybe 30 seconds or more before it became
hot enough for the solder to melt onto it.
Ok, 30s is way too long, if you haven't made the joint in 5s then your iron
isn't powerful enough and you risk overcooking the joint/insulation. The
irons I would use for something like this are 60 or 45w temperature
controlled irons fitted with a large tip but I could probably make the joint
adequately with as standard (cheapie) 25W item. As wire is cheap you
can practice making these joints all day until you've got it right, then move
over and do it on the critical joint.

I didn't notice the PVC becoming damaged, either expanding or melting. It
seemed to me to be as good as before. I'm just a little worried that it
might have melted and become compromised above/below the joint, where I
can't see. On the other hand, I've tested the sockets with devices that draw
large currents - if anything had gone wrong, I'd know about it, wouldn't I?
The problem with overcooking the work is less likely to be in the current
carrying capacity of the joint but in the integrity of the insulation which may
break down after a few years of ageing, not something you would want to
have buried in the wall.

Secondly, I wrapped the joints in electrical tape because I just couldn't
source heat shrink in time. Each joint was wrapped 3 or 4 times, and then
the whole thing was wrapped in more tape.
Not really a good plan as insulation tape ages, its adhesive fails and the
wrap loosens, not the best for the long term. That said, many hundreds of
thousands of houses in the uk have hidden chocolate block joints
(sometimes) wrapped in insulation tape which have not caused problems.
It just seems a shame to start doing the best possible job you can, then
skimp on the details. Personally I use adhesive lined heatshrink on all my
joints, that way it stays where it is put and offers additional strain relief.

I *think* I've done this well enough. One final thing I might do is put the
joints inside fireproof boxes so that in the unlikely event of something
going wrong, they won't set the house on fire.
Nope, if you aren't confident in the job, use a 'pro', HA! there's a laugh, 4/5
would probably twist the wires, wrap it in insulation tape & bury it ;-)

As other have said, no-one can say authoritatively that your joint is good
so it may be worthwhile remaking it after a bit of soldering practice and
using the right sort of insulation.

Btw, my preference is still for soldering over crimping, I've seen too many
badly made joints caused by operator error in choice of crimp and/or tool
setting just waiting for long term failure but that's just my experience.

I'm sure this sounds like a lecture, its not meant to, good luck :-)
--
fred