ECN Forum Forums Code Related Discussion NEC & other Code issues electric cooktop rating

I have varified that 10/2 romex was run from the panel to a crossover point (junction box)and then from that JB to a JB under the cabinet where the cooktop is.The 20A breaker was for the built in oven(3.3KW)They had them wired to the wrong breaker in the panel.ie:30A to oven and 20A to cooktop when the oven was supposed to be wired to the 20A and cooktop to 30A.