Question: how long does it take to heat a fully cooked 12 pound ham?
Answer: Preheat the oven to 350 F. Place the ham on a rack in a large baking pan and add about 1/4-inch to 1/2-inch of water to the pan. If the ham is labeled 'fully cooked' (does not require heating), heat it in the oven for about 10 minutes per pound, or to an internal temperature of 140 F.