From the Manufacturer: Siemens PL series of Load Centers is a premium, feature rich design. The Load Center is single phase, 120/240 Volt, 40 space, 40 circuit and comes with a factory installed 200 Amp Main breaker, a combination Surface/flush mount cover, and Copper Bus Bars. There is no need to purchase ground bars as they come standard in the PL series of Load Centers. Siemens PL series of Load Centers is a premium, feature rich design. The Load Center is single phase, 120/240 Volt, 40 space, 40 circuit and comes with a factory installed 200 Amp Main breaker, a combination Surface/flush mount cover, and Copper Bus Bars 40 spaces/40 circuits ,1 phase 3 wire ,Copper bus ,Boxed