Ok, This is a dumb question...but why do exposed 12v connections, like say on a boat trailer not short or whatever when they go under the water? Why is it just the bulbs that need to be water tight?

12v current still transmits under water from wire to wire even when in contact with water?

thanks

The voltage is low,12v, so it's not as apt to conduct through water as higher voltages will.

Mainly, incandescent bulbs blow because they are hot and hit cold water when backing the trailer in. More of a rapid expansion/contraction of disimilar materials thing than it is an electrical issue. The sockets, being copper or brass, will also corrode/oxidize.

Fresh water is a very poor conductor of electricity. Saltwater however is an excellent conductor of electricity.

12 volt is just too weak to cause much of a disturbance. 110 AC however, is strong enough that even in freshwater, it can cause electrocution around docks with faulty wiring.