I have a desicant pack, and a dehumidifier rod in each of my safes, the rods probably burn $10 worth of electricity a year, very low wattage (12W I think).
My safes are closed ia an isulated room in the gararge, inside safe humidity runs between 50 and 55% all summer, been this way for years, never seen any brownish /orangish stuff on any of my guns.
I have remote hygrometer in the safes that send to a base unit, yes thru the safe,I can read the humidity inside the safe without opening them.
$18.00 at Amazon.
Of course I wax all my guns also.