Hot humid is it down there?? In addition to your dehumidifier rod, swab all iron/steel parts of your guns, including tthe bore, real well with Birhcwood-Casey SHEATH (BARRIER??), then put each one in a silicon-impregnated GUNNY SOCK! This will definitely keep them from rusting!!

I kept my gun safe in the milk room of my barn in central NY for over 10 years, plenty humid, and never got a spot of rust on any of them treated as above. And I didn't have a dehumidifier rod in the safe, either.

Like RebelHog, where I live it is hot and humid or cold and humid (it is texas - don't like the weather, wait 15 minutes!). Most of the time you can swing a stick through the air and it will rain.

So, I use damp-rid and I also have ade it a habit to have a mandintory gun cleaning day once a month whether I have been hunting/shooting or not.

Take the dehumidification ideas in this thread seriously and you should not have an issue with the safe in the basement unless your area is prone to flooding.

Thanks to everybody for your replies. If I can make it work, I plan to keep the gun safe upstairs in the guest room. In the event that my plan is foiled (which happens from time to time!), I will keep everybody's advice in mind and put the gun safe in the basement.