I take the phrase "arrange to drain" to mean that you have one end of the pipe lower than the other as a plumber would with a horizontal run of drain pipe. Everything we use outside can get wet inside, so it needs to drain. That doesn't mean that we want it filling up with water like a plumbers drain, as I guess it was with the old type fittings. I was stating in my earlier post that I might not consider all locations outside to be wet locations.
Looking from another perspective, those old fittings were also letting the water drain back out. As you say, the only real safeguard is that the insulation is rated for a wet location.
Dave
