30 Amp Cooktop on 40 Amp Breaker

Question

The installation specs for my cooktop read as below:

-Connected Load (kW Rating) @ 240 / 208 Volts = 7.2 / 6.2 kW

-Amps @ 240 / 208 Volts = 35.0 / 35.1 Amps

-Recommended Circuit Breaker – 30 Amps

The circuit I have available is on a 240v 40 amp breaker running 8 AWG wire.

First, it's a little strange that the manufacturer lists a 35 amp draw and recommends a 30 amp breaker. I'm guessing that has something to do with the NEC 220.55 Demand Factors table. But according to the table 1 appliance at 8,000 watts divided by 240v = 33.3 amps. I'm stumped there.

Second, it would seem to me that since the cooktop leads will be hardwired in a junction box, there wouldn't be a plug compatibility issue. Then the only problem might be the gauge of the wiring coming out of the cooktop provided by the manufacturer?

Finally, in a separate manufacturer specs doc lists the "Minimum circuit required" as 30 amp... which makes me think that a 40 amp circuit would be fine even though the other doc "recommends" a 30 amp circuit.

Answer 1

The term they are supposed to use is Minimum Circuit Amapcity (MCA) and/or Maximum Over Current Protection (MOCP). In your case the MCA is 30A, but they apparently didn't provide an MOCP, just a "suggested" one. I think you are fine with a 40A breaker, so long as your conductors in the wall to the receptacle are rated for that and at #8, they are.

The rating on any circuit in the NEC is based on "continuous" current, defined as 3 hours or more. On a stovetop, it's highly unlikely that you would have ALL burners set at FULL output for 3 hours or more.