[seharper]

I have tried a single induction burner plugged into the wall and if too many appliances get used it pops the breaker, so the wall circuit is a no go

That's how circuits work normally...

Kitchens are supposed to be wired with two circuits for countertop outlets. Each circuit is 120 volts at 20 amps. That is 2400 watts.

Most kitchen heat appliances are 1500 watts, because that is the hard limit for appliances with normal plugs. How good are you at math? You might have figured out that 1500 + 1500 is more than 2400. So 2 heat making appliances on the same circuit at the same time isn't supposed to be possible. That's why kitchens have 2 circuits.

Now some appliances like toasters and small electric burners are only 800-900 watts. Obviously that's so you can make toast while making coffee and just make it in the 2400W. But those are the exception not the rule. You need to look at the appliance nameplates and know your circuits.

If you want the flexibility to run anything and everythng without thinking, feel free to get some 12/2 Romex and run a separate circuit for each receptacle. You can still overload a receptacle by plugging two 1500W appliances into it, but that's only a 20% overload, and if you look at a breaker trip curve, they're rather tolerant of 20% overloads, so most likely you'll get away with it if it's only for a few minutes.

The only gotcha with this trick is each kitchen receptacle circuit counts as 1500 VA on your house's Load Calculation, so if you do upgrades in the future, an electrician is slightly more likely to tell you that you need a service upgrade.

Yes, that is exactly what I was thinking. I'm glad to hear someone else thinks this isn't a crazy idea. If that is an arguably compliant setup, then it is probably the best option.

It's absolutely compliant, it's to allow one range circuit to support cooktop and oven separates. It is the right way to do that thing.

I agree that it is ok to have an electric cooktop with the existing circuit for the dual fuel range. I never really understood why a standard size dual fuel range needed the same size power supply as an electric range, burners included.

Because if they said "you need a 20A/240V circuit" most people would think they have to install a special circuit for it, and probably not buy it.

 

[curiousburke]

Here's an update and another question.

I figured I would take dcwired's advice and fix the microwave non-compliance issue first by running a new circuit. I opened up the walls a little and pulled the wire. In doing this, I found that it will be more of a PITA to run the 6awg from the stove to the new induction cooktop than it would be to add a new 12/3 dedicated circuit for the cooktop. So, went to get 12/3 romex and it was the same price as outdoor 10/3 wire. That seems more futureproof to me, but is there any reason I wouldn't want to use exterior rated 10/3 for this?

 

[curiousburke]

Here's an update and another question.

I figured I would take dcwired's advice and fix the microwave non-compliance issue first by running a new circuit. I opened up the walls a little and pulled the wire. In doing this, I found that it will be more of a PITA to run the 6awg from the stove to the new induction cooktop than it would be to add a new 12/3 dedicated circuit for the cooktop. So, went to get 12/3 romex and it was the same price as outdoor 10/3 wire. That seems more futureproof to me, but is there any reason I wouldn't want to use exterior rated 10/3 for this?

actually, I can get exterior 12/3 for half the price of the interior 12/3, (indoor is Romex, outdoor is Southwire): it's 12/3 Gray Solid CU UF-B W/G Wire

Is there any disadvantage?

 

[seharper]

I figured I would take dcwired's advice and fix the microwave non-compliance issue first by running a new circuit. I opened up the walls a little and pulled the wire.

While you're running one circuit, why don't you run several circuits and put each outlet on a separate circuit so you never have to deal with breaker trips again. You sound like the kind of person who would benefit from that (i.e. you run a lot of stuff at once). The hard part is the route, once you have access to the route throwing 3-4 cables in there is just as easy as 1 usually.

In doing this, I found that it will be more of a PITA to run the 6awg from the stove to the new induction cooktop than it would be to add a new 12/3 dedicated circuit for the cooktop.

Sure, that's hunky dory if the cooktop instructions tell you it works on a 20A circuit. The NEC rule allowing range/oven to share is mainly for convenience so people don't have to run new circuits. You're certainly allowed to.

So, went to get 12/3 romex and it was the same price as outdoor 10/3 wire. That seems more futureproof to me, but is there any reason I wouldn't want to use exterior rated 10/3 for this?

That is UF-B type cable. It is occasionally found cheaper than NM-B, and that seems to be a weird pricing fluke that may be peculiar to big-box stores.

UF-B is superior to NM-B generally. The only exception is if multiple cables are tightly bunched or sharing a conduit for 2 feet or more, UF-B is derated more severely than NM-B. (The 310.15(B)(3)(a) calculation comes off 60C for UF per 310.15(B)(16) but 90C for NM per 334.80). So, don't do that

 

[Jim Port]

The #10 is fine. It just takes up more space in the box and is stiffer. It is also harder to strip the sheath off the conductors.