According to hankB :
I have an outdoor receptacle (B)that is connected to a GFI outdoor
receptacle (A) via a shielded extension cord-14?.B got wet, corrosion set in
and I plan to replace it.I have been told that an outdoor solid wire from A
to B would be better and that if I used a braided wire unless ALL the
strands are securely attached it might conduct but not be able to handle a
heavy load such as an 120 V electric water heater. True? Is there a way I
can measure whether the braided wire is fully conductive

Generally speaking, solid wire is used for permanent wiring, and stranded
for power/extension cords (in our code "portable cord"). The sheath is
usually optimized for different conditions.

I can't make enough sense out of your description to know whether you're
talking about the receptacle feed, replacing the extension cord, or what.

It sounds more like permanent wiring. Stranded wire is mostly
irrelevant to house wiring (except inside some light fixtures/dimmers,
and certain methods of using conduit and individual conductors,
etc). For extension cords outdoors - especially long term use, it's
almost always highly advisable to use pre-made extension cords with
molded ends, which are both well connected in the plugs (often by welding)
and vastly more water proof.

It's not a good idea to use solid wire in an "extension cord", because
it'll fatigue/embrittle if exposed to any movement. In cold weather,
most solid wire insulations will crack or shatter, and they
won't stand up to sunlight exposure unless they're specifically
rated for it.

It's virtually impossible to measure how well braided wire makes contact
short of overcurrenting the connection (by several times the ampacity
of the circuit) and seeing if it gets hot. Simply not practical.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.