Over-the-range microwaves are the default in a lot of Washington condos and renovated rowhouse kitchens: they save counter space and double as a vent fan. Hanging one correctly comes down to two measurements, both taken to the bottom of the cabinet above it. Get those right, then deal with the wall, the outlet and the vent.
The figures below come from GE's installation instructions for its over-the-range microwave ovens, Pub. No. 49-8699-3. Other brands use similar numbers, but the guide packed with your model is the one that applies.
The installation figures
Mounting space.
- •The cabinet that will sit above the microwave needs its bottom edge 66 inches or more off the floor.
- •That same cabinet bottom needs to be 30 inches or more above the cooking surface.
- •At least 30 inches is required between the side cabinets. Wider openings can be closed with a filler panel kit listed in the use and care guide.
- •So the hood and range lamps are easier to reach, the microwave's bottom should clear the top of the range backsplash by 2 inches or more.
Support.
- •The mounting surface must carry the cabinet's own load plus the 65-pound microwave plus up to 50 pounds of food and cookware, a total of 115 pounds.
- •The microwave can't be installed in island or peninsula arrangements. It must be mounted to both a top cabinet and a wall.
- •The wall should be at least 2-by-4 studs with drywall or plaster and lath at least 3/8 inch thick, and the microwave must be attached to at least one stud.
Power.
- •The unit is rated 120 volts, 14.3 amps.
- •It needs a dedicated branch circuit of 15 to 20 amps feeding one grounded outlet, with the outlet box inside the cabinet above the microwave.
- •Extension cords are ruled out, and a qualified electrician should install the outlet box and circuit.
Venting. Exhaust can go outside through the top, outside through the back wall, or be recirculated, which requires a charcoal filter kit. Outside venting connects to a 3 1/4- by 10-inch rectangular duct, or to round duct no smaller than 6 inches through a transition.
Why these numbers
Distance from heat. Thirty inches between the cooktop and the cabinet bottom keeps the microwave out of the worst of the burner heat and clear of tall pots.
The pair of heights. Taken together, the floor and cooktop measurements define the box the microwave has to fit in, which keeps it clear of the range while leaving the controls within reach.
Weight. Full of food, the microwave is a cantilevered load over the range, carried jointly by the stud and the upper cabinet. Drywall anchors alone can't be trusted with it.
The outlet location. Running the cord up into the cabinet keeps it away from cooktop heat and grease.
Measuring before you buy
- Floor to cabinet. Run a tape from the finished floor up to the underside of the cabinet over the range. You need at least 66 inches.
- Cooktop to cabinet. Measure from the cooking surface to the same cabinet bottom. You need at least 30 inches.
- Opening width. Measure between the side cabinets. You need at least 30 inches.
- Backsplash. Check that the microwave's bottom will clear the range backsplash by 2 inches.
- Studs. Use a stud finder and mark at least one stud behind the opening.
- Outlet. Open the cabinet above. If there's no grounded outlet inside, plan for one.
- Vent route. Check for an existing duct in the wall or ceiling, or decide to recirculate.
DC kitchen notes
- •Plaster walls. Older DC homes often have plaster on wood lath or directly on brick. The guide accepts plaster and lath at 3/8 inch or more, but the microwave still needs a stud. The GE guide is written for stud walls, so if the wall behind the range is solid masonry with no stud, check with the manufacturer before mounting.
- •Short upper cabinets. Some rowhouse kitchens have uppers hung lower than standard. If the cabinet bottom is under 66 inches, it has to be raised or the microwave doesn't belong there.
- •Recirculating in condos. Many condo kitchens have no way to vent outside, so recirculating with a charcoal filter is the norm. Replace the filter on the schedule in the use and care guide.
- •Exterior vents in historic districts. Cutting a new duct through an exterior wall in a historic district involves preservation review. See how hood ducts are sized for the venting side.
When the installation is wrong
- •The underside of the microwave gets very hot during stovetop cooking.
- •The unit tilts or pulls away from the wall over time.
- •An extension cord runs down to a countertop outlet.
- •Smoke and grease linger because the damper is stuck or the filter kit is missing.
Who does what
- •Putting a receptacle inside the upper cabinet, or running a new circuit to it, is work for a licensed electrician. In DC, the Department of Buildings says trade permits must be obtained by a DC master licensed professional.
- •Cutting a vent through an exterior wall or roof is contractor work.
- •Raising or replacing the cabinet above is carpentry.
- •Never open the microwave's cabinet. Microwaves contain high-voltage parts that can stay charged after unplugging.
If an over-the-range unit stops heating, or its fan, light or turntable fails, our microwave repair service covers built-in and over-the-range models. Range hoods follow different height rules; see our hood height guide.
Document referenced
- •GE microwave oven installation instructions, Pub. No. 49-8699-3: cabinet height from floor and cooktop, opening width, backsplash gap, wall and stud requirements, load rating, outlet location, venting options and duct size.