Sparking in a microwave is not uncommon. Food or liquid previously spilt inside the appliance, or grease accumulated on the interior sides or top, may continue to cook during subsequent microwave use.This process may cause arcing or sparking to occur in the internal cavity. Alternatively, microwave energy can concentrate in one area of your oven due to a faulty fan motor or stirrer belt. Finally, a shorted or opened high voltage diode could be the culprit. For parts replacement, it is advisable to consult a certified microwave technician.
Microwaves and Metal
According to physicist Maarten Rutgers, former professor at Ohio State University and currently employed by Asylum Research, placing a solid metal object within your microwave will not cause excessive damage. What can cause problems are metallised foil wrappers with paper or plastic behind them. Microwaves will hit the foil and cause sparking and fire as the heat reaches the backing material. Solid metal will absorb the heat, whereas thinner metal cannot. Glass cookware allows microwaves to pass through, so it is a better vehicle for microwave cooking than metal pots.
Cleaning to Prevent Sparking
Microwave ovens should be wiped clean after each use to avoid the build up of food residue. Many microwaves have glass turntables that can be easily removed, cleaned in soapy water, rinsed, dried and replaced. The internal cavity of the microwave should likewise be cleaned with a moistened cloth or damp sponge. The appliance should be unplugged before cleaning. Adding a covering of waxed paper, cling film or a microwaveable plastic cover before cooking will reduce spills and splatters that can cause sparking.
Burn spots in the microwave oven's interior are an indication that sparking has occurred. Ignoring this telltale sign could lead to a damaging fire inside the appliance. A certified technician can assess the situation and discover the reasons for the arcing and burning. If parts require replacing, the technician will be able to locate what is needed and provide safe replacement servicing. Your microwave oven could give you a serious electrical shock if you are not familiar with its components and the correct way to service the unit.
When microwave ovens first appeared on the market, some amateur experimentation was done to see how different foods would react when exposed to this new technology. One experiment with a halved grape with a tiny connection of skin attaching the two parts produced a lightning effect. The shape of the grape was somehow conducive to receiving and amplifying microwaves. Experimentation of this sort is not recommended and may void the warranty on your microwave.