As I described in this question, I'm planning to mount 12V LED strips under the treads of an outdoor wood staircase. The strips I'm considering are rated IP65. Does the aluminum channel enclosure also need to be wet-rated?
I'm asking because I'd like to use a 16mm 45-degree channel like the one pictured below, and I believe that this channel is IP60, meaning "not water-resistant". I've seen 45-degree channels claiming "IP65 with the right sealant" but those channels are taller: at least 19mm. Even the 16mm enclosure is quite noticeable, so I'd like to I'd really like to avoid taller ones if possible.
The channel will be mounted upside down, so it won't be rained on directly nor will water be able to pool near the strip. Here's a not-to-scale idea of the setup I'm planning to use:
Or is waterproofing these enclosures less about the enclosure geometry and really just about using the right sealant when attaching the diffuser and the end caps?
Conversely, would it be better not to use sealant when attaching the diffuser so that any water that does get in there can drain out the bottom? It's a really tight fit even without sealant, if that matters.
I've done a fair amount of DIY electrical work, but never outdoors or in wet environments so waterproofing is a bit of a mystery to me. Thanks for helping with my novice questions!