[DJ123]

Use GT85 in electrical connections, it is a water inhibitor and helps to protect to electrical connection. You could also use some battery grease/jelly on the outside of this to help prevent water ingress to the connections themselves.
As a final barrier I use Self Amalgamating tape as this is water resistant and works well. I have spotlights on my bike with the connections behind external bodywork wrapped in this. No issues at all in the years I've had it.