Appliance Wiring Question

[diyretired68]

My old electric wall oven with built-in microwave was wired as one unit and required 120/240V, 60Hz electrical wiring. Within the electrical feed, the red and black wires were both split into two before being plugged into the combined unit via a modular device (see picture 1). This line is connected to two breaker-box positions of 40 amps each, tied together (see picture #2).

The oven/micro was 26 years old and needed replaced. I’m unable to find a similar oven/micro arrangement wired together that still fits into existing cabinetry so I’m buying a separate wall oven and separate microwave to replace them. My question is whether or not I’m able to use the split wire feed to power both separate devices and if so, what it would look like. And if that’s not possible, and if I have to use a separate kitchen outlet for the microwave, does that have to be a new dedicated circuit also to comply with code?

The oven is 3,400 watts, 240 volts and must be hard-wired to a 30 amp breaker. The microwave will be 120 volts and be about 1,000-1,200 Watts.

I can do simple stuff (wiring, plugs, outlets, etc.) but if it involves getting into the breaker box, it goes beyond my comfort level. Advice? Thanks in advance.

 

[Snoonyb]

A couple of questions; Will the cabinet depth allow the new appliance to fit appropriately, were there to be a "J" box, surface
mounted, in the cavity?
Is it your intent to have both appliances in the existing cabinet, and if so, will the MW be
uncomfortable, at that height, to use and will a shelf be added for support?

 

[diyretired68]

A couple of questions; Will the cabinet depth allow the new appliance to fit appropriately, were there to be a "J" box, surface
mounted, in the cavity?
Is it your intent to have both appliances in the existing cabinet, and if so, will the MW be
uncomfortable, at that height, to use and will a shelf be added for support?

The cabinet depth allows room for a J box in the area behind the microwave. Both appliances will fit into the same large vertical space in the cabinetry. The oven will be on the bottom (raised an inch or two for ventilation), and then the microwave will sit on a shelf above the oven which is at a comfortable height. These will be at the same heights as the original equipment I had to replace. thanks.

 

[bud16415]

If one of the pros here could explain the breaker setup shown in the photo?



It looks as if there are side by side 30/40 amp double breakers and the center 2 40amps are used as one to control the range and the outer two are also tied together for a dryer.



Why would this be done instead of a separate 30a and a 40a and each control its given device? Is it that each device needs a 120v leg for controls or in this case a microwave. If so wont the 120v leg be breaker to high of amps?

 

[Snoonyb]

Bud, those are common breakers that use both buss bars.

Look at ETON & SQUARE D; 30/40 combination breakers

The appliance is +20yrs and it was common then to transform step-down for controls and ancillary appliances, in the same body.

 

[bud16415]

Bud, those are common breakers that use both buss bars.

Look at ETON & SQUARE D; 30/40 combination breakers

The appliance is +20yrs and it was common then to transform step-down for controls and ancillary appliances, in the same body.

I understand how they work i guess, but what is the reason for using one as apposed to two breakers? Is it space saving.

 

[Snoonyb]

The cabinet depth allows room for a J box in the area behind the microwave. Both appliances will fit into the same large vertical space in the cabinetry. The oven will be on the bottom (raised an inch or two for ventilation), and then the microwave will sit on a shelf above the oven which is at a comfortable height. These will be at the same heights as the original equipment I had to replace. thanks.

Because of the # of conductors already in the flex conduit; Conduit Fill Table, you'll need to run another circuit, I always use dedicated for appliances, for the MW.

Something is off here; "The oven is 3,400 watts, 240 volts and must be hard-wired to a 30 amp breaker.", because 3400W divided by 240V = 14.14A, so, are there 2 ovens?

 

[Snoonyb]

I understand how they work i guess, but what is the reason for using one as apposed to two breakers? Is it space saving.

Yes, that's generally the cased, although, in some cases the main also needs to be increased.

 

[diyretired68]

Because of the # of conductors already in the flex conduit; Conduit Fill Table, you'll need to run another circuit, I always use dedicated for appliances, for the MW.

Something is off here; "The oven is 3,400 watts, 240 volts and must be hard-wired to a 30 amp breaker.", because 3400W divided by 240V = 14.14A, so, are there 2 ovens?

There are not two ovens. It is a single wall oven, and I wrote down the description above from the website. But I just looked at it again, and to be specific, it read "30 amp breaker recommended." thanks,

 

[Snoonyb]

There are not two ovens. It is a single wall oven, and I wrote down the description above from the website. But I just looked at it again, and to be specific, it read "30 amp breaker recommended." thanks,

Thanks, and not to question you, but for clarification, could you provide the make and model #?

 

[diyretired68]

Thanks, and not to question you, but for clarification, could you provide the make and model #?

Empava, model EMPV-24WOC02, 24" built-in electric convection oven

 

[Snoonyb]

Empava, model EMPV-24WOC02, 24" built-in electric convection oven

Thanks.
Interestingly, the information I've found, so far, is that the power requirements are 20A, which would aline with the math in post #7, however, there is a recommendation, to use #8 conductors, which are generally used for 40A, which you likely have now.

So, I'm going to do some more digging.

 

[diyretired68]

OK, but if I put in a new dedicated circuit for the microwave, is there any reason why I can't just wire up the new oven on the old dual 40 amp breaker circuit? Does that make it unsafe in any way? thanks

 

[Snoonyb]

No, there is no reason not to use the existing circuit, as breakered, because the appliance should have internal over-curcuit protection.

The breaker protects the conductors, not the appliance.

I haven't been able to get a response from the appliance wholesaler, yet.

 

[PJB12]

Check the manual and the appliance tech sheet or data plate.
On one of these it most likely tells you the maximum circuit protection amperage. If you go over, the warranty is void.

Also, should the appliance have a problem that causes components to over-amp, you really want the breaker to open before there is a fire in the appliance. As Soonyb mentioned, the branch circuit conductors will be protected.

Personally, I'd consider a separate circuit for the microwave. But, that's just my opinion.

Paul