Heater Electrical Diagram Published August 17, 2013 at 800 × 446 in Electric Hot Water (Liquid) Heater ← Previous Next → Electric Liquid Heater Schematic Diagram. The heater box 2 2000 watt elements run off the Saturn’s high 144 voltage system. This current comes by a heater contactor and 2 20 amp KLK fuses located earlier in Electrical box #1.