Existing 40amp breaker and #8 wire to old range I have removed. I added a box at the removed 240 receptacle. Can I add my new stovetop at 9.6Kw and wall oven at 6.4Kw to this added box?
Your proposed combination exactly fits onto this branch circuit
Since we are putting a cooktop and a wall oven on the same circuit, the provisions in Note 4 to Table 220.55 direct us to treat the sum total of their loads as the equivalent of a single range:
- Branch-Circuit Load. It shall be permissible to calculate the branch-circuit load for one range in accordance with Table 220.55. The branch-circuit load for one wall-mounted oven or one counter-mounted cooking unit shall be the nameplate rating of the appliance. The branch-circuit load for a counter-mounted cooking unit and not more than two wall-mounted ovens, all supplied from a single branch circuit and located in the same room, shall be calculated by adding the nameplate rating of the individual appliances and treating this total as equivalent to one range.
For your cooktop and oven, this gives us 9.6kW + 6.4kW = 16kW of equivalent range load. We then apply Note 1 to this equivalent range load:
- Over 12 kW through 27 kW ranges all of same rating. For ranges individually rated more than 12 kW but not more than 27 kW, the maximum demand in Column C shall be increased 5 percent for each additional kilowatt of rating or major fraction thereof by which the rating of individual ranges exceeds 12 kW.
From that 16kW load, we can derive that it's 4kW over the 12kW upper limit on Column C of the table, so we need to up the 8kW Column C figure by 20% (4 * 5%), which gives us 8kW times 1.2, or 9.6kW as our final answer. This is precisely what a 40A, 240V circuit can handle, so you're good to go.
The circuit you have now 40-amp 240-volt circuit: 40 amps x 240 volts = 9,600 watts
Since the new ovens and stoves operate in about 60% "cycle" mode that would be actual load of 5.7 kW for the Stove.
For the oven same applies. Manufacturer marking 6.4 kW, actual consumption 3.8 kW.
Total consumption with everything on = 9.5 kW.
So you are good to go.
For more details you can read the 17 pages NEC Table 220.55 instructions.