Why does the smoke alarm only go off when you have burnt the dinner?

Question

Why does the smoke alarm only go off when you have burnt the dinner?

Answer 1

To let you know the dinner's done! ;)

There is a sensor in the alarm that detects smoke molecules.  It does not go off if you leave the lid off the kettle, for instance, because that is steam, not smoke.

If there is only a little bit of smoke (eg: from slightly burnt toast) it should go quiet if you bat a tea towel at it, which disperses the smoke molecules.

Answer 2

Set fire to the house and see if it goes off then too.

Answer 3

Simple. If it went off when you had not burnt the dinner then what good would it be?

Answer 4

Food burns long before it smokes. So do pots. I used to work nights and would fall asleep while I was making dinner. I could burn up the whole thing, ruin the cookware and smoke alarm would never go off because there was no smoke and the heat was concentrated. The smell of burning metal woke me up. (boy, did I get skinny!)

On the other hand, my smoke alarm is over my bedroom door. If I don't run the fan when I take a shower, the heat and steam sets off the alarm, from the bathroom.

If I use the broiler, the heat sets off my alarm, if I don't use the fan.

It's always amazed me that my smoke detector goes off when I'm in charge, but it doesn't go off when I'm asleep and have a real fire hazard. I wonder why Teflon pots don't smoke when they get hot, they just get hotter, for hours.

Having said that, I've burnt food and never produced any smoke or more than a very local heat, for hours. My nose and an alert brain are much better.

As an aside, men don't seem to be very alert to smells. They don't seem to differentiate, pay attention and burn stuff, unless they look at it. I was married to a man who thought dinner was done, when the smoke alarm went off.

Answer 5

Oh I cannot stop laughing at Probablygrahams answer to that, classic!!! NOT a good idea to try it though! A smoke alarm will be triggered by the onset of smoke, whether that be burnt toast or a genuine fire. Say you put the dinner on then fell asleep, then you would be glad it went off and woke you up!