Actually a guy posted a response from Suburban on another RV forum. Also based on wikipedia a maximum of three wraps of teflon tape is correct use. Like wiki explains the teflin tape once wrapped and the parts screwed together the teflon fills holes in the metal, but there is still plenty of surface for electrical contact.
Found this too
The role of the sacrificial anode rod
The anode rod is the most important factor in determining the life of your water heater. An anode rod is a steel core wire surrounded with one of three different metals. These metals include aluminum, magnesium, and zinc. The rod is screwed into the top of your water heater and protects your water heater from rusting. When the tank is filled with water the anode rod sacrifices itself to protect the exposed steel of the water heater, through a method called electrolysis. Electrolysis happens when there are two pieces of metal connected inside of water, the process makes the anode rod corrode in place of the exposed steel in your water heater. During this process the more noble (less reactive) metal will corrode over the less (more reactive) noble metal. Aluminum, magnesium, and zinc are all much less noble than steel, meaning they will corrode before the steel, which is why they are used for anode rods.
