And, of course, this is complicated. The "rod" solutions are basically a warm stick. The purpose of which is to keep the internal temperature of the safe above the dew point temperature.
Dew point is dependent on the amount of moisture vapor in the ambient air. The varies by location, by season, and by weather conditions. Just this moment, 1547 24FEB19, here in DFW, the ambient dew point is 23ºF, the RH is 27% with a dry bulb of 58ºF--a nice mild winter day (far nicer than in 2014 when we had an ice storm).
So, if the temperature of the safe is held above 24º, moisture will not condense out of the air on the surfaces inside the safe.
On Friday, the RH rand from a low of 90% to a high of 97%. The dew point was close to the ambient temperature all day. So, if a person had warmed the air to just above ambient (circa 52ºF the whole day) the air would have not condensed moisture out, but the relative humidity would have been well over a 'target" 50% despite.
Sadly, the numbers for dew point and RH are often conflated, and not in a sensible manner. I don't run a rod, but I use a boxed desiccant, but, that's a specific response to my particular climate. If I lived in the PNW I would probably have a mix of rods and trays of desiccant. Maybe. Perhaps. Sadly, there's not a one-size-fits-most answer.