This is a very good question.
For me, the rub is this: Will your enclosure contain a fire?
the primary design consideration for all electrical boxes is not to protect your stuff, but to contain a fire.
When these items are out in the yard, it doesn't seem to be as big of an issue as when they are attached directly to your house.
You have to assume that a fuse doesn't work and that your meanwell PS is on fire in that enclosure.
I'm not saying I have the answers, as others will certainly chime in.
Just saying that the plastic for a real electrical enclosure, or the metal, are made of substances to contain fire.
Not sure about a Harbor Freight plastic ammo can.
If it were me, I'd be using a 'real' metal electrical enclosure.
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