When acid rain falls on bare copper, copper salts are produced that are corrosive to aluminum.
When grounding aluminum cable trays it is common practice to paint the Servet post and the bare copper to avoid aluminum corrosion.
Sometimes the "Monkey see, monkey do" syndrome kicks in and all ground connections get painted.
(By the way, please turn off your caps lock. Thanks)
Bill
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"Why not the best?"
Jimmy Carter