A big point seems to have received little comment in the replies to this subject: Compression fittings are NOT automatically raintight. I believe the standard changed some ±20 years ago and only the ones listed as raintight are suitable for that use. Concrete tight is another standard; and some (mostly set-screw type) require a wrap of tape to remain concrete tight.
If you want to exclude rain, use raintight. And arrange the conduit to drain.
If you want to exclude "moisture", seal the conduit on each end and dry it with something other than 80% humidity air we have in Florida!
It is VERY easy to fail getting the conduit fully seated in both sides of a short compression coupling. Different manufacturers use longer steel sleeves on SS fittings, which seem to make a stronger installation.
As always, the pressures to work faster, use lesser trained and experienced mechanics, and "just get by" can give a bad job using any material.
Lynn Adams Lynn Adams
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