I have a friend who swears AT the scotch locks. When he has to use one in an emergency he fills the lock with silicone before snaping it shut. The silicone helps keep the elements out and helps prevent corrosion.
Notice: in an emergency. As stated in earlier posts, much better methods are available to connect wires.
Ditto for Posi-locks. They are provided in the Eastern Beaver kits (though he'll supply whatever one specifies) and that's a pretty strong endorsement.