Basic advice for an oven bake element house fire (GE JBP24B0B4WH)

Page 2 of 5  


Which could have occured at the end and then the current did stop flowing.

Presumably, you don't touch it when it's on and hot to begin with. But the actual resistive part is inside the element, so you can't touch it.

Probably because the current flow never exceed 40, 50 amps or whatever the breaker is rated at. 10 or 12KW in a small area is a lot of energy, but it doesn't exceed the breaker.


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Donna Ohl wrote:

Um, an arc is electricity jumping a GAP... and it doesn't electrocute you because you are not putting yourself in the circuit by simply touching the element. If you grabbed both sides of the gap, THEN you'd get electrocuted.

Because it wasn't drawing enough current to blow the fuse.
The plug has nothing to do with anything.
Do you really need to spaz out like this every time you have a problem? "What is it? WHAT WHAT WHAT!?!?! Can I fix it? CAN I? CAN I? CAN I?" Jeez. Calm down.
Replace the damn oven, too. If just turning off the oven didn't stop it from burning, there is something else wrong. Fix the element, and you're going to end up with the fire department in your house again, and they'll probably arrest you this time for arson.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The element is normally fed from 240 V. The heat is generated in an inner resistance component which is completely insulated (electrically) from the element's outer metal jacket, which is grounded by touching other metal parts of the oven (and possibly by an explicit ground wire).
In normal operation, the jacket of the element is always grounded, so there's no voltage on it. *But* if the element breaks or the insulation between the core and jacket fails, you can get current flow between the centre core and the jacket - there is 120 V from *each* side of a broken core and the jacket. You could get an arc from the core to the jacket even with a gap in the element - the 240 V path through the element is broken, but there's still 120V at high current available.
The switch *should* disconnect power from both sides of the element and stop any arc when set to off. But if one side of the switch is shorted closed, it would still work normally while the element is intact (the other side would still switch the element on and off). So you may have a problem in the switch.

An arc is not a dead short, and the current is limited both by the voltage drop across the arc and any remaining element resistance still in series. So there may not have been enough current to blow a fuse. Fuses protect wiring from overloads - they aren't designed to prevent fires.
As for whether you should replace the oven: The powder from an ABC fire extinguisher is corrosive, so you need to clean it up very thoroughly. As long as it was confined to the interior of the oven, it may have been possible to clean it up by sweeping and wiping. But the oven is definitely *not* designed to have a garden hose sprayed into it! Unless the interior was already really clean, spraying water into the oven probably carried the corrosive powder into places you can no longer reach to clean.
    Dave
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

This is correct... it is a dangerous failure mode...
Many appliances switch only one side of the 220 line so a fault to ground in the element can't be shut off with the switch...
You have to pull the plug or the breaker.
Yep it's a dangerous failure mode.
Mark
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Any generalizations about which stoves have switches that switch both sides of the line, and which switch only one?
The last time I took apart a failed "infinite heat" control for a range element, I noticed that the bimetallic element that modulates the on/off time had only one contact, and thus switched only one side of the 240 V. But when you turned the control to "off", a second contact opened the other side of the 240 V circuit as well, so the element was supposed to be completely isolated in the "off" position. I don't know how typical this switch is. (And if the second contact stuck closed, you'd never notice in normal use).
    Dave
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

This is correct... it is a dangerous failure mode...
Many appliances switch only one side of the 220 line so a fault to ground in the element can't be shut off with the switch...
You have to pull the plug or the breaker.
Yep it's a dangerous failure mode.
Mark
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 8 Oct 2008 09:05:16 -0400, jack wrote:

Hi Jack,
I used up TWO of the household ABC fire extinguishers to no avail before calling the fire department. This is a picture of the exact fire extinguisher used (this picture is from a previous repair) http://www.flickr.com/photos/donnaohl/2279911402/in/set-72157603933515835 /
I've concluded ABC fire extinguishers are useless on oven fires!
This is what the oven looked like afterward http://www.flickr.com/photos/donnaohl/2923845896 /
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
/

Depends on what is burning. In many cases, closing the door is enough to let it burn out safely. Or the ABC can put our your roasted chicken.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Donna Ohl wrote: ...

Since it wasn't a fire but an electrical arc, that's not surprising.
I like others am pretty much convinced that in the panic of the moment you didn't turn off the oven so the arc just continued.
To amplify on the other questions, an arc is the passage of current across an air gap by definition--until there's a gap, there's no arc.
It happens when the first break occurs the distance between the two ends is so close air the insulating effect isn't sufficient to break the connection and some air is ionized. Once that temperature is achieved, the arc is self-sustaining as more air is ionized and those charged ions are what carry the current across the gap. The gap can (and did) continue to grow while some of the metal in the elements is melted.
In essence, one has made an AC-powered welder or arc lantern.
In general, remember that fire extinguishers are totally ineffective on electrical fires as they are fueled by the electrical source not a combustion source. So, don't try that again.
Also, while easy to say, don't panic and be sure it's actually the oven control you're dealing with not the heat setting or something else and the switch is actually off. Second, just go to the breaker panel and throw the breaker for the range. You should know precisely where it is and which one is the range; if not, that's your next exercise to go find it and make sure it's well marked.
As for the replacement element, I'm sure there are elements available; I have a nearly 30-yr old GE and elements are still available for it. I've used these folks w/ satisfaction...
http://www.pcappliancerepair.com
Looking, I think you've a typo in the model number is a large part of your problem -- I'm guessing it's actually JBP24BB4WH and the broil element would be
http://www.pcappliancerepair.com/cgi-bin/detail.cgi?item=WB44T10009&brand=GEH
although you'll want to check for sure on the model, dimensions, etc. This one does show the mid-mount clean cycle sensor at least.
Of course, you could simply go down to your local appliance dealer and pick up one, too...
--
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The best reply in this thread!
I'll add: Take the old element (and pieces of same) to compare to replacement unit. AND: Identify and label ALL breakers in the box!
I've often found it easier to remove the metal access panel on the back of the appliance to disconnect/reconnect the oven elements, since there's often not enough slack in the wires.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
PanHandler wrote: ...

Thanks, seemed like _some_ common sense was called for... :)

good advice as well...

W/ GE, I've never had a problem w/ there not being plenty of slack in the front and at least w/ the current oven there's no actual access to the element from the rear w/o moving other stuff as well (it is one w/ the combination microwave in the oven as well, though).
--
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Donna Ohl wrote:

Hi, Maybe inside oven was drity(greasy)? When is the last time you cleaned it putting it to self clean mode? Something burning and you left the oven door open and did not cut the power off? And fireman had to do it? No fire extinguisher in the kitchen? I have one in the kitchen and another one in the garage.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 08 Oct 2008 09:07:54 -0600, Tony Hwang wrote:

Hi Tony, There was nothing that could burn that was inside the oven. It was clean (it looks dirty in this picture because of all the useless ABC fire extinguisher powder). http://www.flickr.com/photos/donnaohl/2923845890 /
Looking closely at the oven element itself, it's blistered in the spot that was "burning" (perhaps it was arcing as people said but I don't understand how an open circuit can arc and even if it did why didn't it blow the 220v fuse?). http://www.flickr.com/photos/donnaohl/2923845892 /
I had two fire extinguishers in the kitchen (notice the burned teapot on the top of the stove ... I'm rather forgetful and burn a lot of things down). The ABC fire extinguisher was useless on this electrical fire. http://www.flickr.com/photos/donnaohl/2279911402/in/set-72157603933515835 /
I would NOT recommend an ABC fire extinguisher for an electrical fire for anyone ever. It didn't do a thing. Neither did turning off the oven switch. The only thing that stopped it was when the firemen turned off the power t the house.
What I'm trying to find is someone who UNDERSTANDS HOW this could have possibly happened? It just doesn't make sense that an open circuit (see the break here http://www.flickr.com/photos/donnaohl/2923845906 /) could possibly arc even after the switch is turned off?
And, why didn't the fuse blow (it's a three pronged grandfather plug according to the firemen.)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

See my other reply. An arc by definition occurs across a gap which would be an open circuit if the arc was not there. And even when there is a gap in the element, an energized element has 120 V between the resistor core and the jacket (in North America).

You do need to interrupt the current to the electrical fire first. If turning the oven switch to off did not do this, turning off the oven breaker in the house electrical panel would have.

Sure it does. A switch, particularly if it's actually a thermostat, needs to open only one side of the 240 V line to do its job in normal operation. To stop an arc to ground, you need to open both sides of the supply to the element. There should have been some switch that does that, but maybe you didn't use it, or maybe it's defective. (Our oven has a separate Off/Bake/Broil/Clean mode switch, which is not part of the oven thermostat).

Because the wiring wasn't overloaded to the point of endangering the wiring. You can have a pretty dramatic arc without drawing enough current to blow a fuse. Why do you expect the fuse to blow?
    Dave
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 10 Oct 2008 18:31:15 +0000 (UTC), Dave Martindale wrote:

Hi Dave,
Is this what probably happened in my "typical" oven fire?
0. Something (grease perhaps) was on the broil element in one spot 1. The grounded jacket thinned in that one spot, ever so slightly 2. Over time, that one spot cracked, ever so slightly 3. Over time, stress increased on the resistor core encased in concrete 4. At some point, the cantilever stress broke the inside resistive core 5. I heard a "sound" as the air gap ionized to a conductive plasma 6. The core melted, causing the plasma gap to expand (more sound) 7. The super-heated plasma conductivity extended to the metal jacket 8. The core-to-jacket arc melted the jacket "backward" in a spiral pattern 9. I turned off the broiler but that only reduced to half the pressure 10. The other 120v pressure still allowed the plasma to remain heated 11. The plasma arc spiralled backward toward the remaining 120v pressure 12. Opening the house circuit eliminated the pressure & the "fire" went out
Is this what happened? Did I miss any steps?
Donna
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

That's it. I'M OUTTA HERE.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I don't think we know why the element failed. Oven elements routinely get organic stuff (food) splattered or dripped on them, and the usual result is a bit of smoke as the organics stuff gets burned to carbon or ash, while the element is completely unhurt.
So, either your element was defective somehow (e.g. a gap in the insulation somewhere, or it was subjected to some unusual stress at some point. The initial failure could have been an open resistor core, but it could equally well have been the core touching the grounded metal jacket.
By the way, the insulating fill is not concrete - concrete contains lots of water and doesn't like being red hot. It's some kind of high-temperature insulator (e.g. a ceramic).

All of that's possible, though we don't know for certain.

Substitute "voltage" for "pressure". Electrical voltage is in many ways like fluid pressure, but they're not the same thing. This assumes you turned off the switch, but the switch only interrupts one side of the 240 VAC line.
Yes, turning off the house breaker removed the voltage, and the arc ceased. Turning off the circuit breaker for the stove alone would have accomplished the same thing.

We don't know for sure what happened (at least I don't). But the sequence is plausible.
    Dave
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Steve Barker DLT wrote:

Hi, What is definition of arcing? Current jumping across a gap. When element is cracked(in the process of breaking up) it can arc. Just take the bad element out and go to HD or Lowe or appliance parts store and get a matching replacement. No brainer replacing burned out element. Just make sure connection is good and tight.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

It may not be THAT easy. My wires only pulled out about and inch and bolting the new element on was very difficult.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 8 Oct 2008 00:13:06 -0500, Steve Barker DLT wrote:

Hi Steve,
I can't find the part number for the GE jbp24b0b4wh oven upper heating element replacement. http://www.flickr.com/photos/donnaohl/2923845890 /
Do you know of a good web site (GE doesn't have them even at their parts web site http://www.geappliances.com/service_and_support/parts /
Donna
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.