Night out. Come home and decide to have a pizza. Fall asleep. Wake up, house smells horrible, black chunk of carbon in the oven.
Did I nearly burn the house down? I’m thinking 425 is not hot enough to ignite, it just makes the house smell horrible. I know something left unattended on the stovetop is very dangerous, but what about inside the oven?
Even if it had ignited, the fire would soon run out of oxygen.
Things like this (I’ve experienced them a couple of times!) make me wonder though: why on earth aren’t all stoves equipped with a timer?
I did it with tortilla chips I had fried up and was letting drain out with a rack and cookie sheet. I accidentally turned up the oven way high. Each chip had a tiny flame, like little corn candles. No real danger, tho, just a smelly mess to take outside.
The fire would not run out of oxygen because ovens are vented. They are also made out of metal and insulated so even if a piece of pizza caught fire it’s unlikely to set the whole house ablaze.
This sorta thing happened when I was a teen. Except it was a pizza box left in the oven.
Mom freaked. My position was leave the oven door CLOSED, turn of the oven itself and wait it out.
Mom’s postion was open the door, allow oxygen in, and then spray it with a giant fine powder spewing fire extinquisher.
It was years before the whole house was finally de powdered.
Now even Mom knows to leave it alone should that occur again.
Well, there is a small vent on the top of the stove, just enough to let fumes escape. There is no air inlet. I doubt it would serve to keep an actual fire burning more than half a minute or so.
Yep, I was right. I just did the experiment: I took a couple of old newspapers, tore them to shreds and soaked them in grease (by using them to wipe off my stove top), then shoved them into the oven, set them on fire and closed the hatch. All visible fire went out within 15 seconds.
(There’s still some smell in the apartment though; luckily, as a precaution, I disabled the fire alarm! I’m opening a window now.)
You haven’t shown anything. You’ll have to repeat the experiment with the door open.
Billfish’s mother already has provided the complementary experiment. See above!
Not quite. Very different set of flammable material, and again no control experiment to compare to. In addition you’re experiment is not reproducing the conditions in the OP. You’ll have to start over, use pizza, set the oven to 425, and then go to sleep for a while.
I set something on fire in the microwave, it was just smoldering and smoking but even in that state would have sold well to a caveman wanting to start a fire.
on a more theoretical and general level, the question is if something will burn from being in the oven relates to its auto ignition temperature as it is unlikely there is an ignition source in the oven (spark or flame).
The thing is, if something is likely to catch on fire just from being at oven temperature, it will likely do it even if its just in the oven for the normal cooking period (30-180 minutes??) i.e. pretty much soon after it gets to the working temperature it will ignite, or it never will. So unless your oven is on thermal runaway for some strange reason, falling asleep shouldn’t matter a dime. Except your food is ruined. So if its safe to cook when awake, its safe to cook when asleep 
As others mentioned anyway any fire will likely consume available o2 very fast and self extinguish.
If it has a high water content, it will have to dry out before it can ignite.
True enough, I misspoke I guess. I mean it will likely catch fire within the cooking period, not necessarily “soon after” its hit working temp, IMO.
Many microwave ramen packages have a warning to fill up to the line, OR ELSE! “This will catch fire! Really! Flames and all!” (Paraphrased. :p) I haven’t seen it myself, but I came by just after a third party had put one out. Very messy and smoky.
Also, as IDtenT Error notes, food has to dry out before it burns. The center of the piece will take a while (hence the instruction “Make sure the center reaches 160 degrees.” or whatever), and meanwhile moisture from the inside will be cooling the outer layers.
This might be the subject of a thread on its’ own, but what would it take to install a timer between the (three-phase) outlet and the usual domestic stove?
The (1-phase-to-ground) electric outlets in typical laundry rooms are (at least in Scandinavia) always equipped with a timer, which can be set to no more than 120 min., for the use of ironing clothes.
Why is there no equivalent for stoves?
I suspect that it’s because a certain subset of Americans, dying out thank God, that like to keep a kettle on the boil ready for–what?–at any time. Because microwaves are SCARY, and will IRRADIATE you. Plus, there are folks that cook low and slow.
Finally, I could just picture the Safe-T-Stove shutting down in the midst of cooking a 32# turkey for Thanksgiving.
My mother ignited the microwave once, and burned countless kettles dry. I, however, specialize in setting greasy broiled food alight. And yes, the items will burn out.
Oh, I’m something of a slow cook myself. And I think microwaves are from Satan.
Still, while slowly cooking my traditional ox-tail stew, it doesn’t strike me as much of an additional effort to reset the timer once every two hours.
Or have an override. I’d pay extra for auto off, just to end the “did I leave the stove on” worries.
Ray Bradbrury suggests that paper ignites at F 451.
The way to burn down the house is to fill up the oven with flammable gas, and then as it starts emitting flames out the vents,
open the door and have the flammable gases spill out and up … eg into the curtains