I am finally replacing our single electrical convection oven with NOS double unit that we purchased as a clearance floor model a couple of years ago. I have a run of 35 feet and the badge on the unit says it is 7.2 KV at 240/120 v. or 5.4KV at 208/110. The installation guide says NEC requires four conductor connection on new construction, but the next paragraph says I "must use a three-wire, single phase A.C. 208Y/120 04 240/120 Volt 60 hertz electrical system." I'm interpreting the latter is for use in an existing system. I intend to use new wire, and am thinking 3 wire 6 gauge to the junction box where the ovens whip will connect. Is this wire adequate or overkill and would a 45A breaker be appropriate? Or is this something I shouldn't be attempting myself? I have a little electrical experience, enough to have added a sub panel to my wood shop with several 110 and 220 circuits, but am hesitant to proceed without some pro help. Also,does the 208/110 on the badge describe a 3 phase circuit?