I have an existing 30 amp wall oven in my house and recently purchased a combination microwave/convection oven that will go above it (replacing a 110v microwave). In terms of existing wiring in the cabinet where both units will be installed, I have a standard 110 outlet for the microwave (shares a breaker with our fridge), and a 220 outlet that the wall oven is wired up to.

The manufacturer says the new unit requires 240v (not 110 like most of these combo units), since it's a high watt microwave and convection oven combo. So here's my question: Can I use my existing 220v wall oven outlet and run both the existing wall oven and new microwave/convection oven combo?

Some details that might help: A double pull 40amp breaker feeds the outlet from my breaker box. I'm unsure of the wire size but imagine it's up to code (house is 10 years old). Oven calls for 30 Amps (240v), and new microwave/convection oven calls for 20 Amps (240v)--and specifies 30 Amps for "circuit Amps @ 240VAC" --whatever that means!
link to the new unit is here if helpful: KitchenAid®: Welcome to KitchenAid.com

Can I wire both to my existing 240v outlet? If not and this requires me to add additional breakers to my service and then run new wiring and an outlet--could I do so by securing the new wires (in conduit if needed) to the interior wall of my garage (instead of cutting into the sheetrock)...and then do the rest of the run under the house like some of my other wiring?

Thanks for any help!

Read more: Adding a microwave & convection oven to a shared 220 plu - DIYnot.com - DIY and Home Improvement

 

Two cooking devices can share a circuit but the total recommended circuit for both exceeds the existing circuit so I would install a new circuit for the microwave/convection oven.

Yes though I would suggest conduit all the way. You could use PVC in the garage and switch to ENT under the house for ease of installation and run #10 THWN all the way.

 

Because the full-load current of the new M-W is 20 amps , a 20 amp breaker would trip unless the 20 amp current flowed for only a very brief time-period , so a 30 amp CB is needed with #10 conductors.

You will need a seperate 30 amp Branch-Circuit for the new M-W. Good Luck , enjoy the new M-W.!!!

 

Thanks so much to PATTBAA and Ray--really apperciate your helpful thoughts. A couple of quick follow up questions before I roll-up my sleeves and take care of business.
1. (To PATTBAA's reply)--Is there any chance i could replace the current 40amp double pull breakers with a 60amp (or whatever the best size would be) and proceed with sharing the existing circuit? If the answer depends on the gauge of wire that was run, I'd be happy to look at this if you can let me know what the minimum size requirement would be to make this option (possible option) work.

2. If not (To Ray's reply)--Is the idea to use PVC for cost effectiveness, and then switch to ENT as i'm guessing it's flexible or provides some other benefit?

Thanks again.

 

Not without replacing the existing cable unless it is #6 which it probably isn't.

Yes. You could run ENT all the way also but it was a matter of appearance that caused me to suggest PVC in the garage since being rigid it is easier to get a good looking installation. Cable could be used but the ENT may give some resistance to rodents under the house.

 

Thanks so much Ray. I really do appreciate it.

 

That's what were here for.

 

One more question on this one. I just received the microwave/convection unit. It has a pig tail with 4 wires and a flexible metal wrapper around it (no male plug). Does it make sense to wire in an actual outlet to the wall and a male plug to the unit, or is this something that can be solved by wire nutting the unit to the new wires i will run?

 

Hard wiring is obviously what was intended by the manufacturer or there would have been no pigtail. The pigtail is not suitable for a plug.

 

You will need a proper connector on the end of the flex metal tail.

 

Is it acceptable to use the proper size wire nuts for 3 #10 wires then?

 

Why three wires.? You have one line in and don't you have one load out?

 

That's a goof on my end. I was thinking I'll have a double pull breaker for 220--and would have 2 hots coming off it that would tie to 1 wire on the microwave/convection end. I'm now guessing there will be 2 hots, 1 return, and one ground--on both the microwave end and coming from the wall (when i wire it). I'll have to do my homework to see how this works for 220. If you have a quick description for me--that helps too. --And of course, assuming i understand this part, is it okay to use wire nuts for 2 #10 wires to make the connection?

 

There will be four wires. There will be two hots one neutral and a ground. All wires that carry current to the appliance are also returns so saying one return is inaccurate.

A wire nut can be used for two #10.

That is a very scary statement and makes me wonder if you know the basics. That would result in a dead short. Maybe you should call an electrician.

 

Thanks. Just wasn't thinking there for a minute (something I will absolutely do before tackling this job of course). And yes, am not an expert and am actually planning on having an electrician inspect my work and make the final hook up at the breaker box. Thanks for your help in getting me ready for the pro to look things over and make the connection. I do appreciate it