It depends upon the type of cooking appliance.

A domestic type electric cooker cooker consists of several boiling rings, at least one oven, and often a grill. The assumed load is less than the total consumption of each component, on the grounds that simultaneous use of all rings, ovens and the grill is most unlikely.

Common practice is to take the first 10 amp, plus 30% of the remainder. Example -total loading is 50 amps. take the first 10 amps and 30% of the remaining 40 amps which is another 12 amps. Add 5 amps if the cooker outlet includes a socket outlet. Most common types of cooker will need a 32 amp MCB and cable to suit. Some larger models may need a 40 amp MCB and cable to suit.

Do not reduce the cable size below the rating of the OCPD.

For a specialist or industrial cooking appliance the above is not generally applicable. For example a large oven in a food factory may operate continually at full load. If it says 41 amps on the rating plate, then in my view it means 41 amps and not some lesser figure. Needs a 45 amp MCB and cable suit. 

It depends upon the type of cooking appliance.

A domestic type electric cooker cooker consists of several boiling rings, at least one oven, and often a grill. The assumed load is less than the total consumption of each component, on the grounds that simultaneous use of all rings, ovens and the grill is most unlikely.

Common practice is to take the first 10 amp, plus 30% of the remainder. Example -total loading is 50 amps. take the first 10 amps and 30% of the remaining 40 amps which is another 12 amps. Add 5 amps if the cooker outlet includes a socket outlet. Most common types of cooker will need a 32 amp MCB and cable to suit. Some larger models may need a 40 amp MCB and cable to suit.

Do not reduce the cable size below the rating of the OCPD.

For a specialist or industrial cooking appliance the above is not generally applicable. For example a large oven in a food factory may operate continually at full load. If it says 41 amps on the rating plate, then in my view it means 41 amps and not some lesser figure. Needs a 45 amp MCB and cable suit.