Bonfire in the microwave

Ah yes. Butter wrappers. The AOL CD of the culinary world as far as microwave ovens are concerned.

Nick

Chris Hogg brought next idea :

Metalised foil wrapper?

Depends on how you describe it. I'd say it was foil-backed greaseproof-type paper. The foil will eventually separate from the paper, given enough manipulation.

Well what would you expect? Kilowatts of rf near a conductor?

Brian

Kilowatts? In a domestic microwave? What bollocks!

When a microwave oven advertises its power as "700W" or "900W", is that the AC mains power consumption or the RF output power? Does a microwave convert almost all the mains power into microwaves?

"Kilowatts" may be only a slight exaggeration if a 900W oven outputs 0.9 kW of RF.

It's the RF output. My 700W microwave uses about 1kW. It's also a 'D' rating which takes into account the size of the oven but I don't think anyone bothers to use the letter ratings which were dreamt up by our Min of Ag Food and Fish or whatever. I don't know which way the letters go in any case.

Well, yes; brain wasn't engaged (I'd just got up and was getting breakfast!).

But why don't I get sparks from a steel wire rack that goes in the microwave to support stuff up nearer the grill?

Chris Hogg laid this down on his screen :

Because it is all firmly and electrically connected together, so no heat can be generated across a conductive junction. You can leave a singl fork or spoon in your mix to microwave, but never put two in where there might be light contact between them, or where an item might contact the metal case.

How do you suppose the metal case survives in a microwave?

Ah, so if it's a single metal component not in contact with other metal parts via a dodgy connection, it's OK?

The rack has rubber feet, and sits on the glass turntable when you want to use it, so no connection to the case or any other metal bit.

The screen in some cheap coax cables is a strip of metallised plastic wrapped round. In some types where it overlaps it doesn't make contact with itself so the cable a 'leaky feeder' !

Bill

Because the grill uses radiant heat? Because of the design of the rack and the wavelength of the microwaves?

By the way, my microwave platter is steel...

It's a Kenwood K30GSS13, and has a Grill/Microwave combo setting, when the grill comes on for several seconds, then switches over to microwave power for a similar period. AFAIK they don't both come on together, I assume to limit the power consumption BICBW. You can use the grill alone, but bearing in mind the speed that my butter-paper caught fire, even a second or two when the microwave switched in would be enough to make it spark if it was going to.

Pass

See HB's reply?

Ah well. Perhaps it's an Amstrad microwave oven in which case that would be 900w rms, 1800w music power or 3600w peak music power, innit?

Nick

Yes!

It is easier/simpler for them to say no metal items put in the oven, but no point in using a metal dish to heat food in the dish.

It's not always safe to put metal in your microwave, as you found out with your butter paper.

well its about 600-900W usually so almost a killer what...

They are quite close.

Does a microwave

yes,

I think the material may have changed recently, at least for some manufacturers. The wrapping used to be as you describe, metal foil backed paper (or even plain waxed paper) but the butter and margarine I use nowadays has a metallised foil plastic, which shows the classic plastic property of trying to return to its origiinal, flat shape when unfolded. The older wwrapping showed the metallic property of retaining the shape it had been folded to.