Single branch circuit for a cooktop and not more than two ovens. 220.55 Note 4

[David B Rivera]

We are covering Chapter 20 of the Delmar's residential book. Special Purpose outlets for Ranges, Counter mounted Cooktops and Wall mounted Ovens. (17th addition.)
We typically do not this use type of branch circuit but it is found in older existing homes.
Fig. 20 on page 449 show a 6600 watt oven and a 7450 watt cooktop fed with a single 50 amp circuit.
The 50 amp branch circuit with 50 amp wire is tapped with 30 amp wire for the oven (6600/240=27.5), and 40 amp wire for the cooktop (7450/240=31.04)
I don't have any issues with the taps, just the 50 amp individual circuit. The below calculation using notes 4 and 1 of 220.55 showing a 40 amp circuit.

Note 4 of Table 220.55 Single branch circuit for a cooktop and not more than two ovens.
6600 watt oven and a 7450 watt cooktop on a single branch circuit.
Add the two appliances and treat as one range
6.6kw+7.45kw =14.05 kw
Note 1 of Table 220.55 ranges over 12 kw
14kw-12kw=2kw
2*0.05=0.1
1.1*8=8.8 kw
8800/240=36.6 (40 ampere)

I know that exception 1 of 220.19(A)(3) shows a 50 amp circuit.
Is this the minimum amperes for this type of circuit and where is the 50 ampere derived from?
(Side note) The example calculation in the 2014 NEC Handbook is a 50 amp circuit.

 

[David B Rivera]

Maximum over current protection

Maximum over current protection

If you use 422.11(E)(3) Single Non–motor-Operated Appliance, any single range of 8 3/4-12 kW in column C of table 220.55 (8 kW demand) could be fed with a 50 amp circuit.
8000/240=33.33*150%=49.99 (50 amps)