Is my plan for connecting a new electric oven sane?

Question

I'm remodelling my kitchen. Currently it's set up for a plug-in electric range, with what looks like a 14-50R outlet, fed by a 3-8 AWG cable protected by a two-pole 40 Amp breaker.

My new setup includes a built-in oven and a gas cooktop.

The new oven needs to connect to a junction box. The oven spex say it draws 4500 W of power and a 20 Amp circuit is "recommended", presumably for each of the two phases it wants. The cable supplied with it is aluminium-shielded 3-12 AWG, rated for 150°C.

The cooktop needs its own 120V supply (via a plug-in cord), just for the igniter.

I understand that I can't connect my new oven to the existing 40 Amp circuit, so my plan is to feed that circuit into a small subpanel and install a two-pole 20 Amp breaker to feed the new oven, and another, 1-pole, 20 Amp breaker for the cooktop.

Does that sound right?

Answer 1

That is an absolute ideal way to do this. Except that a subpanel requires a 30" wide x 36" deep working space in front of it. That may be tough to do in a kitchen - no cabinets, appliances, etc. can be in that space. If you have a place in the kitchen where you can install a subpanel with proper clearance, great!

If not:

• Use the existing cables.
• Replace the breaker with a 20A double-breaker. Make sure that's the right size - 4500W / 240V = 18.75A - with a continuous derate (not necessarily needed here, but raising the issue) it would require 18.75 x 1.25 = 23.4A --> 25A breaker. But if it is UL or ETL listed and the instructions say 20A breaker then that should be the right size. (40A is definitely too big!)
• For the cooktop circuit, you can connect that to one of your regular kitchen countertop circuits. This is one of the exceptions to the "can't share the kitchen countertop circuits with other stuff" rule.