Is it safe to use a portable microwave in a confined shelfspace?

Question

I have an 900 watt emerson microwave that looks similar to this one:

It weighs about 30 pounds and the outside dimensions are about 19" (W) x 16" (D) x 12" (H).

We normally have it sitting on the kitchen counter space but my significant other would like it put in a more discrete location and suggested moving it to a semi-permanent location in the cupboard shelf.

I'm reasonably certain that it'll fit in the shelf and am confident that the shelf could hold the weight (and any heavy items we cook) but I'm concerned about ventilation. The manual says:

Ventilation: Do not block air vents. If they are blocked during operation, the oven may overheat and eventually cause oven failure. For proper ventilation, keep three inches of space between the oven’s top, sides, rear and the area where the unit is to be installed.

The shelf would have that 3" breather room but not much more. Does that sound OK? Am I worrying over nothing? Is there anything else I need to be conscious of here?

Answer 1

Microwave ovens do not generate heat themselves, but cause the food itself to heat up. As such there is not a lot of heat output from the unit, but there is expanding air as the food warms the air in the chamber.

Reputable manufacturers are fairly conservative about their venting requirements. If you meet those requirements, you should be OK.

Another consideration is clearance for the door swing and for moving dishes in and out of the unit. Make sure that its positioning does not cause you to be handling a hot dish at an awkward angle. Also high shelves are a bit risky since you would be handling hot food at head and face level. A singed hand pulled back could lead to a bad scalding.

Finally, you need to be sure that there is an outlet nearby of the proper amperage. A 900 watt microwave draws about 8 amps. A line with a number of other heavy duty appliances on it may pop circuit breakers.

Answer 2

As long as you meet the minimum clearance requirements your microwave will be fine. The shelf above may have some issues with the steam and moist air that will be released from the heated food. Watch for damage if it unprotected wood or a laminate.

Answer 3

I installed a medium size microwave in our newly remodeled kitchen in the fall of 2012. The microwave sat in an open shelf with the back and both sides closed, so that the microwave sits in the enclosure with the door accessed freely. The microwave began malfunctioning, some buttons don't work and at times it doesn't respond even when resetting it. A repair person came out and diagnosed the problem as the control unit assembly needs replaced for $287. I declined the repairs and decided to find a replacement microwave. Speaking with an appliance knowledgeable tech, once he learned the situation and where the microwave is installed he said "the microwave is dying of suffocation (no air flow). Only above oven (built-in microwaves can be installed in a confined area). So, We decided to get a counter top microwave since the space available in the cabinet is too small for a built-in one. Microwaves should last a minimum of 10 years or more, not 6. And yes, a dedicated circuit is a must. I hope that helps answer the question.