On Sat, 11 Mar 2017 21:11:58 +0000, Bill Wright wrote:

Normal cables will not stand semi-permanent immersion in water for very
long.

The length of bog standard Cat5 that is in a U shaped length of
flexable conduit between house and shed seems OK and it's been there
for over 10 years. Initially installed with ends of conduit in house
and shed but it's not strimmer proof... it's been flooded for a good
number of years Cat5 is carrying DC and low speed data from the
weather station sensors, rather than ethernet. Another length of cat5
showed no signs of degredation after several years exposed to the sun
on the southside of the house.

There is a joint in that cable orginally a leaf spring terminal block
inside an inverted open plastic bag but that went rusty and failed.
Join is now soldered and sleeved (just each wire), shoved up inside a
cut off, inverted, open, flat plastic bottle. That's probably been in
out there for 6 years and is fine and is carrying ethernet now.

As for the OP's problem. Is the cable entry a proper gland? Will the
plug pass through gland without the seal in place? It is possible to
cut the actual sealing gland to get it round the cable and assemble
as normal. The cut seals just like the gland to the cable under the
pressure from the tightened gland nut.

If using a seperate IP66 box and glands don't forget to drill a small
weep hole at the lowest point.

--
Cheers
Dave.