Great question — answering as the UphillTech team:
Building a roof over the pedestal will help. The weatherproof covers and relay work well in most conditions. There may be a breaker trip in extreme weather. Around our condo building the in-use outdoor covers work great for the plug in fountains. No problems. The relay boxes for the well pumps are fine as well. The pump start draw would probably cause the GFCI to open, which is why it is not recommended.
Full answer by RMDman: https://diy.stackexchange.com/a/298003 (CC BY-SA 4.0).
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