shrink wrap for wiring

Home Depot or Lowes.

Wire nuts are still code.  Nobody solders light fixtures.

wire nuts and salt water, hmmmmn,,,,,,  ok, I used heatshrink, a soldering iron and silicone on top of all that,
 there is the stuff 3m makes that will make the scotch 33 electrical tape waterresistant, home depot and slowes sells it in there electrial dept.

but of course that was after the power strip nearly caught fire. ( it was smoking.)

Wire nuts do best for me.  Every other type of connection has worked loose on me eventually.  The only thing I do , is put some of that liquid electrically tape stuff on the wire nut opening.  It seals it very well, but also comes apart easy at a later date.   But I like to water proof anything electrical as much as possible.