Can unplugged irons cause fires?

May 16, 2009 8:35 PM

Can unplugged irons cause fires? One of my housemates (Housemate A) observed that my other housemate (Housemate B) put the clothes iron back into the cupboard without letting it cool down. How dangerous is this?

The iron rests upright on a wooden shelf, in a confined space. Lets say that immediately after ironing his clothes, Housemate B puts the iron on the shelf, and unknowingly knocks the iron over while closing the cupboard door. If the iron falls face down on to the wooden shelf, how much of a fire risk is this? Assume, for arguments sake, that it's a standard iron that was used on the highest setting (but is unplugged when put in the cupboard).

posted by tomargue to science & nature (16 comments total)

No risk, because wood will not ignite at 250C.
posted by floam at 8:38 PM on May 16

It's far more likely that it'll burn someone, or leave a mark on a table or shelf or whatnot, than that it'll actually cause a fire.
posted by box at 8:38 PM on May 16

Thanks floam, yeah, that was my thinking.

Yeah, good point, box...I agree. That's actually a concern of Housemate A: he's the only one on the lease, and Housemate B doesn't mind too much about causing damage!
posted by tomargue at 8:45 PM on May 16

Now, it might be possible that a 250C object touching wood for a long time might eventually do some things approaching scary. To ease your mind on this issue, I'm too lazy but I'd suggest:

Look up Newton's Law Of cooling, and figure out what temperature the iron will be at after being turned off for 30 seconds in the air, and then a few minutes of sitting on the wood (use a heat transmission coefficient around 80 W/m^2 K for iron->wood, 6 for iron->air.)

It'll very quickly get to temperatures where it's even "more" not going to cause a fire.
posted by floam at 8:48 PM on May 16

Yeah, yeah, that's a good idea to use Newton's Law of cooling...since I'm lazy, too, might see if wolfram alpha can solve it...
posted by tomargue at 9:08 PM on May 16

Where does the 250C figure come from? ('Cause as Ray Bradbury tells us, some things will ignite at <235C…)

My gut feeling is that you could maybe scorch the wooden shelf, but that's about it. You could always test it: take the hot iron, turn it off, immediately put it face down on a 1x6 board covered with a sheet of newspaper. Keep an eye on it, just in case my gut feeling is 'way off.
posted by hattifattener at 9:31 PM on May 16

How about buying a single floor tile and placing on the shelf under the iron. If it falls face down, it will fall on the tile, which can take the heat. Much easier than asking anyone to change their habits.
posted by metahawk at 9:33 PM on May 16

One other factor to consider is that it may not set the shelf on fire, but the residue from the hot metal touching the shelf will be on the iron the next time someone goes to iron their clothes. Since one usually irons clothes that are special for special events, it may ruin someone's day.
posted by effluvia at 10:14 PM on May 16

It's really not worth it— Housemate B should be able to appreciate the unnecessary risk of putting a hot iron away.
posted by a halcyon day at 10:50 PM on May 16 [3 favorites]

Good point "a halcyon day". We've had quite a problem with Housemate B. Although I would say the iron is low-risk, it's unneccessary. And he takes many more unneccessary risks with the house, knowing full well he's not on the lease. Housemate A has given him many warnings, and is at the end of his tether....

It's an odd situation for me, I'm unused to housemates feuding like this!

Good points, too effluvia, didn think of that. I'd say that Housemate B would be kicked out if that happened.

Yeah, personally I'd do a quick experiment, hattifattener, I'll pitch it to Housemate A.
posted by tomargue at 1:21 AM on May 17

My mum always told me your wait for it to cool before you wrapped the cord round it. Just in case the cord came into contact with the plate and melted.

That would be bad.
posted by Helga-woo at 3:45 AM on May 17

The biggest risk would be a melted cord as Helga-woo says (big surprise for the next person to plug it in!) The next would be if A goes to get the iron and doesn't know it's hot, and burns himself.

To be honest though, it sounds like the bigger problem may be housemate B's disrespect for housemate A in general. That may be worth a separate askmefi with more detail.
posted by ArkhanJG at 5:53 AM on May 17

What if the iron were to come into contact with something fairly thin and flammable, such as tissue of some kind? If that catches on fire, it could catch something more substantial on fire, and then the whole house could go up in flames.

Not sure about the physics of that, but it seems like it would be possible.
posted by jayder at 7:20 AM on May 17

Yeah, ArkhanJG, that has at least 3 or 4 metafilter posts in that one there...actually, I'm encouraging Housemate A to get an account.

You're, right, jayder, other stuff on the shelf is an issue...it is possible to remove stuff from that shelf. However, as a matter of principle we shouldn't be letting our lives revolve around Housemate B.
posted by tomargue at 8:22 AM on May 17

Why take stupid risks with no gain? Get a tile for the shelf.
posted by theora55 at 9:41 AM on May 17

Housemate sounds like a careless jerk. DTMFA.
posted by radioamy at 12:28 PM on May 17