Why can there be a metal rack in a microwave, but we can’t put anything metal in it? Sparking in the microwave is a common thing. ARCING OR SPARKING – METAL RACK . If it's grounded, energy won't build up and you won't have sparks. Or the rack doesen't have ANY sharp points and perhaps is also grounded. There are two types of metal rack in a microwave. Maybe when the rack is in the microwave, it is grounded. Arcing or Sparking – Metal rack issue Cause Did the microwave oven come with a metal rack? I don’t think there is a specific rule preventing “anything metal”. Earn 10 reputation in order to answer this question. If the unit came with a metal rack, be certain that the rack is installed properly on all four of . If there are any damaged spots, touch them up with microwave … The paint on the interior of the microwave might be chipped. Liquid spilled inside the appliance of a microwave or grease accumulating on the interior sides of your microwave is believed to cause sparking in the internal cavity. You’re right, the rack is metal. It would have the same effect on all metals. Check the interior of the microwave for any spots where the paint has chipped away. the plastic support brackets in the case of over-the-range models. To use a rack in a solo oven, begin by consulting the user's manual. It is specifically designed so that the gaps between the rods of the rack are large enough to prevent sparking and to allow the microwaves to pass through. $\endgroup$ – Peter Shor Aug 12 '13 at 1:52. add a comment | Highly active question. If the paint is chipped, the interior metal will be exposed, causing the microwave to spark or arc. That's why microwaves can have metal racks which are designed so as not to spark in the microwave oven. My guess would be that's just the way its engineered. If not, sparking … The reputation requirement helps protect this question from spam and non-answer activity. It isn't because of the type of metal, I don't think.