Wiring for new 40 amp wall oven and cooktop

applianceskitchenswiring

We are upgrading our wall oven and cooktop. The old units were rated for 30 amps each and the new units require 40 amps. We have a 200 amp main panel with one 40 amp breaker for the oven/cooktop that feeds 600 volt 3-6 aluminum wiring to a subpanel. The subpanel currently has one 30 amp breaker feeding NM-B 10-3 to the cooktop and one 30 amp breaker feeding NM-B 10-3 to the oven. As both the new cooktop and wall oven each require 40 amps, what is the best way to proceed? Is the single 40 amp breaker in the main panel and the 3-6 wiring to the subpanel sufficent to meet the load demands of the new 40 amp units?

In response to the questions, the NM-B wiring can be easily replaced from the subpanel to the oven and cooktop. Replacing the 3-6 wiring would be much more difficult, as it is routed behind walls and over drywall cielings. The subpanel could be physically removed. The insulation for the 3-6 is grey plastic/vinyl. I have attached a couple of photos of the wiring and subpanel. I should also add that I plan to hire an electrician to do the work, but would like to know what to expect and, if possible, run some of the wiring beforehand to reduce the labor cost.

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EDIT:
At the main panel the aluminum strand attached to the bus bar in the subpanel is attached to the bus bar in the main:
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EDIT:
Thanks for all the responses. The subpanel is in the basement immediately below the kitchen floor underneath the wall oven. The main panel is on the opposite side of the house. I have attached additional photos of the 3-6 cable below.

The cooktop is a Kitchenaid downdraft (KCED606GBL). The oven/microwave combo is a Bosch Series 800 (HBL8752UC). Kitchenaid nameplate indicates 10.8 kw @240 v:
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Bosch oven is 9.6kw @240 v:
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Bosch microwave is 3400 w @ 240 v:
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Additional 3-6 photos:
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Best Answer

My first concern looking at the subpanel is if that bare #6AL is in fact a ground and the two appliances are straight 240V then the two white wires connect to the buss should have some green tape on them. If it's not a ground but actually a neutral, where are the grounds? You will need to ground everything.

I would try utilizing the #6AL XHHW since changing it out would be difficult. It is rated for 50amps according to my chart so the breaker in the main panel should be changed to a 50AMP. Since the two NM-B cables can easily replaced, change them to NM-B 3#8 and replace both breakers in the subpanel to 40 AMP.

Where actually is the subpanel?

News flash: The name plate on the oven states "four wire". Major game changer. The new wire you run will have to have a ground. This will probably require you to change the #6AL run to 3#6cu plus ground or just run two 3#8 with gnd, one for each appliance, add additional breaker in main panel. Both breakers would be 40AMP and eliminate the subpanel.

If your owner's manual states that you can hook up the four wire appliance to a three wire source, then it is ok to do it.

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