Dumb question (I am really good at
those...):
Would an incandescent light bulb (Say 40w)
in the bottom of the safe do the same
thing as a golden rod?
Is the rod simply more cost effective since it produces only heat, not heat and light?
It would likely do the same thing. I do think the 150 degree heat of the goldenrod is excessive (of course, everyone apparently swears by them so who am I to judge), but I can't tell you which is more energy-efficient. Using an incandescent is an old trick some craftsman use to keep tools from getting condensation/rusted in an otherwise unconditioned workshop. You build a closet or box to put the tools in with an incandescent light. It's just there to keep the tools constantly above the dew point. i.e. without it, the tools get cold overnight and then suddenly get bombarded with hot moist air when the shed or workshop gets hit by the sun, but not fast enough to heat the tools before they get condensation on them.