Microwave manufacturers produce different microwave designs for built-in cabinet holes and for countertop or open-concept settings. The design of each differs in terms of vent placement, as countertop microwaves do not have a wooden frame that surrounds the unit like built-in microwave designs. Despite the difference in designs, it is possible to install a countertop microwave in a cabinet unit if you do so cautiously.
Checking Vent Placement
Examine the countertop microwave to locate all vents on the two sides, top and back panels. Since a countertop microwave is designed to rest on a countertop, the vents are often placed on the sides or top to ensure the vents have proper air space to clean out dust and expel hot air during operation. These vents cannot be covered in the built-in hole, as it may cause the microwave to overheat or malfunction.
Built-In Microwave Placement
Place the countertop microwave in the built-in hole. Adjust it so each vent area has at least 1 inch of space in front of it. Do not push the microwave all the way against the back panel of the cabinet, and do not force the microwave into the cabinet space if the side panels do not provide enough space for the vents.
Cabinet Wire Adjustments
The microwave must be plugged into a grounded electrical outlet, meaning you cannot use a power bar or an extension cord to make the microwave function. If there is an electrical outlet in the back of the cabinet panel, simply insert the cord there. If the outlet is present on a nearby wall, make a small cut in the cabinet's side panel so the cord fits through.
Cleaning and Maintenance
Remove the microwave from the built-in cabinet hole every three months or so to clean the microwave vents. Even though the appliance is designed for countertops, it still collects dust in the vents on the top, sides and back of the microwave. In addition, the cabinet's panels prevent the dust from flying out of the cabinet completely, so that it will not clean out automatically. Use a damp cloth when the microwave is turned off to remove obvious dust and particles from the vents.