In an effort to try to save some dough (pun intended) during these dog days of summer, I turned to the fridge. :-). Normal people, like myself, buy a fridge and turn it on and never even think about the temperature that the fridge is set at until, perhaps, you realize that food is spoiling. So I began a search to find out what the best temperature is for the fridge to see if it is set too high or too low.
You would think that just a few degrees difference wouldn't really matter very much, yet it does. Too warm by just a few degrees and your food will begin to spoil, bacteria like Salmonella, E. coli, and C. botulinum will grow, mold will flourish, and just bad things overall will happen. Yet too cold, you begin to waste energy (think about your home thermostat and how a few degrees will save you 10% of your energy bill),and your food will freeze resulting it going bad quicker because it's not preserving the food.
So from what I have read and researched the temperature for the fridge should be set somewhere between 0oC and 5oC (or 32oF and 41oF), with the best being around 3 or 4 Celcius. The variations really come from who you are asking and probably your lifestyle. For those non-scientific folks, the people at howstuffworks say between 35 and 38 degrees F (1.7 to 3.3 degrees C), but the food and drug administration recommend that your fridge be at or below 40oF or 4oC.
For those of you who are prone to power outages, it's good to know that if your home loses power and your fridge is at 4F or higher for less than 2 hours, the food will still be safe to eat according to the FDA, as long as you don't open the fridge constantly :).
Australian food authority: