Be careful, 5200 is not a sealant
, it is an adhesive. There are a number of places where 5200 is not the best choice. BoatUS magazine had a good article a few months back comparing different adhesives and sealants and the pros and cons of each.
I'd be concerned placing any wiring
in 5200 simply because you'd destroy the terminals, terminal block, and wiring
if you ever needed to work on it in the future. 5200 is designed for substrate failure before the bond breaks. Also, 5200 is not compatible with plastic.
Some 3m 4000 UV should do the job nicely. I used it to bed
my solar panels
and fittings where the wires run though deck.