Yes, the plot thickens... If one electrician declares the wire as undersized but the former electrician did not, there is an obvious difference of opinion. Code is code however and must be met for the sake of safety. Wire size could be a code issue if it is 30A breaker but wire size would not cause more current. Undersized wire can cause a voltage drop and subsequently higher current on impedance loads such as a motor but on a resistive load it would cause less current. This is evidenced by the rating plate that states that at 208V, it draws 4125 Watts and at 240V, it draws 5500 Watts. I think the electricians have some 'splainin to do.