MICROWAVE OVEN ON TOP OF STOVE
Dear Mr. Electrician: How does one go about installing a microwave oven over stove? I would like to remove the hood over my stove and install an over-the-stove microwave oven in its place.
Answer: If you already have a hood with fan and light mounted on the underside of the cabinet, you can possibly use that circuit to power your new microwave oven over the stove. You should determine first what circuit is powering the hood.
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Turn the hood fan and light on and then flip off each circuit breaker to see which one powers the hood.
With the hood circuit breaker off, take note of what else is off in the kitchen and the rest of the home. If you see that the lights in the kitchen or lights and outlets in other rooms are off, then you should not use that circuit to power the microwave.
If only some of the electrical receptacle outlets on the kitchen counter top are off and it is a 20 amp circuit, then you can probably use that circuit for the needed outlet in the cabinet above the stove. Be advised that not every home is wired the same and what works in one home does not make it okay in another.
There are several makes and models of microwave ovens that mount under the cabinet that is located above a stove. The instructions for mounting the microwave are fairly common and explained in the manual that comes with the purchase of a new microwave oven.
You should read the installation instructions before purchasing an over-the-range microwave oven, but basically you mount the wall bracket and drill some holes in the cabinet above. The instructions will tell you what the minimum distance must be from the bottom of the microwave oven to the top of the stove. If kitchen cabinet above the stove is too low, you cannot install a microwave oven over your stove.
Below are two examples of microwave oven installations that I did a few years ago. There is a chart of adjustable electrical boxes at the bottom of this post.
The difficult part is getting power to the microwave oven. This is accomplished by installing an electrical receptacle inside of the cabinet above the stove, which should be done before mounting the microwave oven on the cabinet.
One tool that I have found to be very helpful for installing an outlet for a microwave oven over the stove is the Oscillating Multifunction Tool. It seems to be the perfect tool for cutting clean precise holes in woodwork. This is a tool that I always kept on my truck because it came in handy often.
REMOVE THE OLD HOOD FROM OVER THE STOVE
Make sure that the circuit breaker for the hood is off. Remove the small cover underneath the hood that contains the electrical connections. Using a non-contact voltage tester, check to make sure that the power is off. Disconnect the wires sticking out of the wall from the wires on the hood. Do not cut the wires.
Tape the bare ends of the wires coming out of the wall with electrical tape. Take note of the type of connector used to clamp the cable coming into the back of the hood. If it has a locknut, remove it by unscrewing it counterclockwise. If the cable connector is blue plastic, you can cut it using diagonal pliers. Be careful not to cut the cable or wires in the cable.
Once the cable in the wall is free from the hood, you can remove the hood. There are screws in the back, on the sides, and sometimes on the top under the hood that all must be removed to get the hood down.
Be careful when removing the old hood. That same wire that is feeding the hood will be used to power an electrical receptacle outlet for the new microwave oven. Do not cut the wire. The new microwave must be a minimum height distance from the top of the stove. Before purchasing the microwave oven, look up the installation manual online at the manufacturer’s website to get the installation details.
To power the new microwave oven, an electrical receptacle outlet must be installed in the cabinet above the stove. The power cord from the microwave oven will come through a hole that you make for it in the bottom of the cabinet and plug into that outlet.
It may not always be possible to use the old hood electrical feed to power the new microwave oven. The existing wiring might not be a 20 amp appliance circuit. The wire may be too short to relocate where it is needed. In some cases a new 15 or 20 amp, 120 volt circuit would need to be installed if specified by the manufacturer.
Some microwave oven manufacturers require a dedicated circuit for their microwave. Read the installation instructions before purchasing an over-the-range microwave oven. They can be found on the manufacturers website.
ELECTRICAL OUTLET FOR MICROWAVE OVER STOVE
The easiest way to install an electrical outlet using the existing cable is to bring the cable up inside the wall and through a homemade hole in the back of the cabinet that is above the stove. Then you can bring the cable into the back knockout of a 4″ square electrical box and just mount it on the surface of the back of the cabinet. You may have to remove a cable staple or two in the wall to get the length of wire needed.
A larger hole may have to be cut in the wall to free the cable in order to get enough length to move it further up. Cut the drywall with a compass saw held at a 45 degree angle inward to make it easier for patching. You can see an example of this on another one of my posts here.
I usually mount the electrical receptacle outlet recessed in the wall to give it a neater appearance. You will need to cut a hole in the back of the cabinet for this. My post on installing an outlet box in an existing wall may be helpful to you.
In the photo above a wall stud is against the left side of the box making it ideal to attach the box. The metal box must be grounded by attaching a copper pigtail wire using a 10/32 machine screw. The pigtail gets spliced together with the the grounding conductor in the feed cable and an additional pigtail to connect to the outlet.
See me blog post about grounding outlets and switches for more grounding information.
MOUNTING MICROWAVE OVEN ON TOP OF STOVE
Every over-the-stove microwave oven has a mounting bracket that gets attached to the wall. There are also holes that need to be drilled in the bottom of the cabinet for the power cord, and for screws to hold the microwave oven up.
The mounting bracket and the screw hole pattern differ from each microwave oven. Therefore it is important to follow the instructions that were supplied with the microwave oven. Templates for holes are usually supplied with each microwave oven for over-the-stove use.
The wall bracket must be screwed into at least one solid wood stud in the wall as it carries most of the weight of the microwave oven. It is important to have the bracket line up with the center line of the microwave oven.
The big hole above was made using a slow speed drill (400 RPMs) with an inch and a half hole saw, so that the microwave oven electrical cord can pass through to the new electrical outlet above. Holes were also drilled in the bottom of the cabinet for two support screws that keep the microwave oven level.
I have installed microwave ovens over-the-stove by myself, but it was always a challenge. I would put my 4′ ladder under the cabinet and put a folded furniture pad on top of the ladder. Then I would muscle the microwave oven onto the top of the ladder with the furniture pad under the oven. From there I would lift the oven onto the wall bracket and then try and catch one of the top screws that come through the cabinet. It is much easier to install the microwave oven with two people.
If an air duct was connected to the above microwave oven, the work would be a little more difficult and require the skills and tools of another trade. Read the manufacturer’s installation instructions before commencing with this work. There are height restrictions with respect to the distance from the top of the stove.
I recommend that you read the installation instructions of any appliance before you buy it. Many manufacturers have the instructions downloadable online.
ANOTHER MICROWAVE OVEN OVER STOVE OUTLET INSTALLATION
On the job that the above photo was taken, the client wanted a microwave oven installed over her stove. However the existing kitchen cabinet over the stove where the hood was attached was too low. The microwave oven would have been much lower over the stove than the manufacturer’s specifications would permit.
Fortunately the homeowner had a friend who was a cabinet maker. I removed the old kitchen hood, and then he came and removed the cabinet and took it to his wood shop to cut it down to size. It was a multi-step and multi-trade job installing this particular microwave oven.
While the cabinet was gone I was able to cut in a new electrical outlet using the existing appliance circuit that was connected to the old hood. I cut the hole in the drywall while holding my compass saw at a 45 degree angle inward. This gives me an angled edge to secure the cut piece of drywall when I put it back.
The larger grey cable in the wall is going down to supply power to the range receptacle.
You can see the ground wire above tightly screwed to the back of the Steel City #MB120ADJ one gang adjustable metal electrical box.
All of the edges of the hole and the cut out piece are buttered with Joint Compound for walls and then the piece of drywall is pushed into place.
The joint compound oozes out from the edges. I push the piece in just enough so that it is even with the wall, then I smooth it over.
The Joint Compound needs to dry overnight before a second coat can be applied. After that dries it can be sanded and painted.
It is difficult to see in the above picture, but there is a paper template that is furnished with the microwave oven taped to the underside bottom of the cabinet. This is for marking where to drill holes for the power cord and the mounting screws. It is very important to attach the template correctly to ensure that all of the drilled holes line up with the microwave oven.
It is a little bulky, but I can usually muscle the microwave oven over stove into place by myself. I move the stove and put a 4′ ladder under the cabinet with a folded furniture pad on top. I get the microwave on top of the ladder and from there lift it onto the wall bracket.
With it hanging on the wall bracket, I am able to push the oven up enough to catch one of the screws through the cabinet. I have to do this while also pushing the power cord through the drilled hole in the bottom of the cabinet. Much easier with two people.
The above chart lists the PVC and metal adjustable electrical boxes originally made by Carlon and Steel City, both of which were bought by Thomas and Betts, which was then bought by ABB. The product names may be confusing to search engines so you should use the part numbers when looking for these products. The metal adjustable boxes are gangable.
When shopping for electrical boxes or other electrical materials, it is best to have the manufacturers part numbers of the specific products that you are looking for. Many times I have searched online databases of electrical supply companies searching for specific products by name with poor results. As soon as I punch in the part number I find exactly what I am looking for.
Click here to see more photos of an outlet box being installed using Madison Bars.
I also installed recessed lighting in the kitchen on the top of this page. Click here to see the work involved.
Click here to see a kitchen hood replacement.
All of my articles pertaining to kitchens can be seen by clicking here.
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