On Tuesday, 17 September 2019 08:33:34 UTC+1, The Other Mike wrote:
On Mon, 16 Sep 2019 06:58:02 -0700 (PDT), harry
wrote:

On Monday, 16 September 2019 10:24:52 UTC+1, Tricky Dicky wrote:
When I re-site the CU the cable to the shower will need extending this will be a temporary measure until we do the bathroom following the kitchen.. Once the bathroom is done this cable will be redundant, unfortunately part of this cable will be buried in plaster. I am hoping as it goes through the loft I can pull a few metres of new cable through. If I cannot replace the cable the join will be in an inaccessible place in the loft or buried in the plaster. Can I use crimps in either of these situations and what additional insulation do I need to use eg. heatshrink, self amalgamating tape or other?

Richard

You can join cable with solder ferrules. (A tube in which cables are soldered using a blowlwmp) No crimping tool needed.
All sizes of cable can be thus joined.

https://uk.rs-online.com/web/c/cable...r-sleeve-kits/

In the main these sleeves are used for connecting earthing pigtails onto
screened signalling cables.

Whilst they can join large diameter cores they are not specifically tested nor
certified by the manufacturer for carrying any level of current.

--

Of course they are.
The underground electricity distribution system depends on soldered joints. On aluminium as well as copper cables.
I spent years installing them.