One Way To Splice a Power Cable

[DIYSwede]

-Thanks for the tips Rick, and AFAIK your splice will be at least as strong as the original.
Depending on your local code & applicable regulations,
I'd think the heat shrink & -sheath should be of proper thickness and grade for the applied voltage.
One caveat though when it comes to fatigue strength of soldered joints thru bending forces*.

Personally, I always do staggered splices (even for lo-voltage duty), and use the thickest possible heatshrink for the wires,
build up the missing sheath thickness over the spliced & shrunk wires with self-amalgamating rubber tape,
and finally slipping the heatshrink sheath over, with 2 extra inches of shrink overlap added on each side.
*Thus each wire steadies the others in the tight bundle, and the cable is more prone to bend in the supple cable,
rather than at the relatively much stiffer splice: hopefully offering less risk of fatigue breaks.

But then again - that's just my two precautious cents.

Cheers
Johan

-Yup - even after some 35 years it does happen at times that I forget to put the heatshrink on before soldering...