Commercial ovens generally have two kinds of voltage 380v and 220v two kinds of voltage commercial ovens in the factory are set up two kinds of voltage universal that is to say, connect these two kinds of voltage can only depend on your actual situation to allow if it is best to connect three electricity (380v) as well so that can ensure that in the peak period of electricity is the normal work of your oven to connect the two-phase electricity that is the four wires to the two wires in parallel to become the two-phase electricity, so that the two-phase electricity is the two-phase electricity to the four wires in parallel to become the three-phase electricity. I hope my answer will help you