friedegg

Thank you Marc. That's the most technical response I've gotten--thanks to all of you, by the way. I used the term "shielding" informally: I meant only that the design must be intended as such to cause the magnetic field lines to be present above the glass (to induce current and heat in an iron pan or pot) and not be present to as great a degree below the chassis. If the design of the unit allowed as great a field immediately beneath the chassis as above the glass, then metal utensils in shallow drawers just beneath the chassis would heat up as the pot above would (explaining the 12" safety distance to a combustible surface underneath). But I refuse to believe they would even allow such a devise as that. We were talking about say, a metal can, in a wood drawer underneath and in close proximity to the bottom of the chassis. If that can contained matches for example, a magnetic field would induce an electrical current and heat in the metal of the can, which could in turn ignite the matches, which could ignite the wood drawer, etc.. I do understand you cannot induced a current in wood. What I'd like to know is that for a new, properly operating unit, just how strong is that field (if any) just below the chassis? And what circumstances would cause the unit to suddenly develop a stronger field there? I assume that coils of some design in the unit generate the magnetic fields above each pot circle (on the glass). Perhaps the engineers fear the coils could unmount and fall to the base of the chassis, unintentionally delivering more of the field underneath--and so possibly heating up some metal there. Think that's on track?

I understand they do recommend underneath clearance to combustible surfaces that are greater than for regular electric (and here I'm referring to glass top) stovetops--but I have not researched and compared for specific safety clearances. I'm curious as to the circumstances that might conspire to start a fire. RKenny made a good point that some yahoo could store fireworks and gasoline inside a metal can in a shallow drawer just under the unit, and then IF some downward shielding failed or for any reason the induction became directed downward, well, trouble could ensue! Maybe that's their thinking--the inducer isn't going to heat up metal that's a full 12" away even in the worst scenario, and if it heats up the top on an oven underneath then no problem, it's designed for that heat.

The induction effect has to be directional--up--as in focused above the glass top. The base of the unit itself is sheet metal, I think steel (ferrous), so the effect has to be shielded toward the up direction. An oven mounted directly underneath is also housed in sheet metal. There was some mention of ventilation needed for "components" in the unit--but mounting an oven 1" beneath the base of the induction unit would provide for no ventilation, plus the heat of the oven would add to any temperature issue. Makes no sense; doesn't add up--that's why I was looking to someone here for a technical explanation. The GE Tech Support people were of course no help--they have memorized the words "twelve inches" just fine.

Kurt, do you have some technical expertise with these?

I bought a GE Profile induction stovetop and I'm shocked to find out the manufacturer recommends 12" clearance below the base of the unit to any combustible surface underneath, like to a drawer. I just don't see the undersides of those units getting that hot. The idea is to induce heat in steel above the glass ABOVE the unit. A friend has another brand induction stovetop and says the bottom heats up a little but not enough to ignite something. Anyone know why (other than lawsuits) the manufacturer would set such a distance?