A thermal system includes multiple thermal elements, multiple power lines, and a control system. Each of the thermal elements define a resistor and a current limiting device, and the thermal elements include at least a first subset of parallel thermal elements and at least a second subset of parallel thermal elements. The current limiting devices in a given subset of parallel thermal elements have opposite polarity from each other. The multiple power lines are connected to the plurality of thermal elements. The power lines are configured in pairs for providing power to the first subset and the second subset of parallel thermal elements. The control system is configured to selectively apply power to the first subset and the second subset of parallel thermal elements by way of the power lines.