Electric heaters are typically designed for use in water. They work fine for a primary distillation, however, if you do a spirit run (2nd distillation) where your abv is around 50%, that can cause problems. Water is an excellent absorber of heat, ethanol not as much, so when the element is at full power, the expectation is that in water conditions and certain amount of heat will be removed from the elements surface, with ethanol that is not happening.