As for the CU, I guess you could use sealant if you have direct surface clipped cables entering the CU, but it would be better to cut entry holes in the housing that are the right size for the cables.
standard test finger ipxxbIP2X is the finger.. not the wire...
416.2.2 A horizontal top surface of a barrier or enclosure which is readily accessible shall provide a degree1mm is IP4X, and from a brief look in the 17th, the IP4X requirement in the 16th for horizontal surfaces seems to have been removed.
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