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How plausible is this?? #145229
03/09/06 09:50 AM
03/09/06 09:50 AM
Trumpy  Offline
Joined: Jul 2002
Posts: 8,260
SI,New Zealand
Tonight, I turned out to a kitchen fire.
(K-88 for Rodalco)
The kitchen was wrecked and only ashes to work on.
I have pics but I can't post them because they are part of evidence now.
I will later though.
Now the lady of the house insists that she switched the electric kettle on in an ad break on the TV.
She heard the kettle switch itself off (Bimetallic switch).
Later realisng that she was making a cup of tea, she opened the door to the kitchen only to find the kitchen engulfed in flames.
The blast upon opening the door knocked her over.
What I am asking is this, just how likely is it that an electric kettle could switch itself back on and boil to the extent where it ran dry (without the bi-metallic strip bending) and start a fire (all in the period of approx 10-20 minutes).
The reason I'm asking this guys is because this sounds really bloody dodgy.
I'd invite the opinion of fellow Station Officer Ray (RODALCO).
Also, if you were knocked over by the accumulated heat and fumes,etc from the kitchen, wouldn't your clothes be burned slightly, or have a bump on the back of your head?.
And also with a brass door knob set, wouldn't you burn your hand on it?.
None of that took place.
This is rather strange, almost insurance strange.
Anyone is welcome to jump in and have a crack, the more the merrier I say!.
This is just going over and over in my head.
A kettle cannot as far as I'm aware switch itself on.
I could be wrong too.
Your thoughts. [Linked Image]

{Message edited to add missing word}

[This message has been edited by Trumpy (edited 03-09-2006).]

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Re: How plausible is this?? #145230
03/09/06 02:12 PM
03/09/06 02:12 PM
geoff in UK  Online Content
Joined: Dec 2002
Posts: 196
Well the mechanisms in the ones I've had apart are pretty cheap and cheerful affairs, and I certainly wouldn't rule out failure in the ON state. e.g contact welding
On the other hand there is usually (always ?) a secondary over-temp device which would have to fail too.
Also, if it did dry up I would have expected an element melt-down which would fuse the supply rather than a conflagration.

Re: How plausible is this?? #145231
03/09/06 06:19 PM
03/09/06 06:19 PM
aussie240  Offline
Joined: Jul 2005
Posts: 223
Blue Mountains, NSW, Australia
Assuming it was a cheap modern plastic kettle, there would be a thermal fuse which typically melts at around 130 degrees. Maybe there was no thermal fuse...I have seen some appliances imported and sold which I'm sure have never been approved (well I wouldn't approve them, or is it just that approval standards have fallen?)and I know NZ gets the same appliances as Australia does.
The older kinds of electric kettle were either in a stainless steel enclosure with sealed element or a porcelain jug with exposed element. With both these designs, the element merely burns out fairly quickly and safely when there's no water.
Hard to really comment further without knowing more about the kettle.

Re: How plausible is this?? #145232
03/09/06 07:54 PM
03/09/06 07:54 PM
renosteinke  Offline
Cat Servant
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
I say "bunk."

First of all, I am quite familiar with the type of kettle you describe....usually has the element exposed, suspended just above the bottom of the pot; plug it in, it works; unplug it and it stops.
I have seen many instances of these things boiling dry- to the immediate failure of the element.
Even if the (automatic) kettle were to somehow fail to shut off, or to turn itself back on...the only loss would be a ruined element.

Now, let's assume the element is encased in the baseplate. Those types I have seen where the element got hot enough (after boiling dry) to melt the aluminum base. There should be some evidence of this, if the thing actually caused a fire.

Now- for another scenario. If the kettle in question is a simple cylinder in shape ("coffeepot" rather than "teapot")....well, I have seen those used, filled with oil, as an improvised deep-fryer. Now that could very easily create the conditions described- especially if there was a gas burner (with pilot light) to ignite the oil vapors as soon as air was introduced.
Of course, if you had a gas burner- why bother frying in the kettle?

Re: How plausible is this?? #145233
03/10/06 03:08 AM
03/10/06 03:08 AM
briselec  Offline
Joined: Dec 2005
Posts: 141
Brisbane, Australia
Have you any evidence that it was the kettle that started the fire?

Re: How plausible is this?? #145234
03/10/06 04:31 AM
03/10/06 04:31 AM
RODALCO  Offline
Joined: Dec 2005
Posts: 857
Titirangi, Akld, New Zealand
It's interesting to note that nothing was noticed in the house prior to the kitchen being fully engulfed in flames.
Normally there is bound to be noise of exploding bottels , cracking sounds of glass etc, or the roar of a fire unless the occupier of the house was deaf.

Also a smell of burning would be noticeable unless the kitchen was on the other end of the house then the lounge.

The house obviously didn't have a working smoke alarm if any.

As already mentioned by our other electrical friends, usually the fully enlosed elements will have a meltdown and the resistance wire within the earthed element casing will short out to earth, blow the fuse or trip MCB, or just go open circuit.
It may cause a molten blob of aluminium and steel on a benchtop or smoulder, but to trigger a K 88 kitchen fire may require further investigation.

The plastic 'made in China' kettles usually have an enclosed element, cant comment how well they melt or burn.

I think fire safety and Trumpy should have a very close look at the actual switchboard of the house what type of fuses, mcb's or 4 inch nails are used on the power circuit concerned. [Linked Image]

I do recall that in the early 1990's here in Auckland we had a couple of spa pool fires, up to K 99 house fires due to 8 kW spa pool elements melting the pvc pipe after the thermal cut out contacts welded shut and the flow switch failed at the same time.

A change in the control circuit was the solution to prevent more of these fires and to use a 40 Amp relay which was triggered via the above mentioned switches.
Now the thermal and flow switch had only to carry the control cct current and the risk of welding contacts did'nt happen anymore.

The product of rotation, excitation and flux produces electricty.
Re: How plausible is this?? #145235
03/10/06 04:37 AM
03/10/06 04:37 AM
RODALCO  Offline
Joined: Dec 2005
Posts: 857
Titirangi, Akld, New Zealand
Sorry, I forgot and am blind myself.

Re-reading your topic Mike, the lady heard the jug switch off, so she can't be deaf then and the lounge can't be on the other side of the house, otherwise you wouldn't be able to hear the 'click' of the switch.

The kitchen door knob would be hot to the touch and yes there would be burned or singed hairs, because she wasn't wearing B.A. when opening the door or stay low as a firefighter would do.

[Linked Image] [Linked Image]

The product of rotation, excitation and flux produces electricty.
Re: How plausible is this?? #145236
03/10/06 07:04 AM
03/10/06 07:04 AM
IanR  Offline
Joined: Dec 2004
Posts: 328
Palm Bay FL USA
Hey guys,
This is perhaps a stupid question from an ignorant, non-firefighing yank. But, I'll ask anyway. What does K88 and K99 mean? Intensity of the fires?

Re: How plausible is this?? #145237
03/10/06 08:45 PM
03/10/06 08:45 PM
RODALCO  Offline
Joined: Dec 2005
Posts: 857
Titirangi, Akld, New Zealand

Standard arrival messages for first truck on the scene.

K 55 MVA ( motor vehicle incident )or special service, like washing off petrol spill.
K 66 rubbish / grass fire
K 77 nothing showing, investigating further
K 88 property fire apparently small.
K 99 property fire well involved.

[This message has been edited by RODALCO (edited 03-10-2006).]

The product of rotation, excitation and flux produces electricty.
Re: How plausible is this?? #145238
03/10/06 11:07 PM
03/10/06 11:07 PM
yaktx  Offline
Joined: Feb 2003
Posts: 288
Austin, Texas, USA
I have seen many instances of these things boiling dry- to the immediate failure of the element.

Cheap plastic kettles in the US are usually 1kW. We have one, and swear by it. When we go to visit a friend who doesn't have one, we go out and buy one as a gift. Beats heating up teawater on the stove. Sure, I often forget and leave it boiling longer than I intended, but I have yet to boil it dry. They're cheap enough to indulge a controlled experiment, although I have never wanted to do that.

Bottom line: 120V, 1kW. Aren't the kettles down under (and presumably in the UK) a higher wattage? (And 240V of course.) I suspect these factors could alter the degree of fire hazard.

I am not a firefighter but I do say I must doubt that one could open the door to a kitchen fully engulfed in flames without at least some burns!

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