An optimized multiple floating guard ring structure is investigated for the first time as an edge termination method for high voltage 4H-SiC planar devices. Simulations were performed to investigate SIC guard ring termination, and determine the optimum guard ring spacing for planar diodes with up to four floating rings. Simulated optimized designs predicted breakdown values from 40% of the ideal breakdown with a single ring, to 84% of the ideal value for diodes with four rings. Implanted 4H-SiC pn diodes with optimized guard ring designs were fabricated and results correlated to simulation. Experimental breakdown values of 1.2-1.3 kV for guard ring structure with four rings were in good agreement with simulated results.