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What can cause a heating element to deform this way? enter image description here My oven is tripping the breaker whenever I turn on the heating, LCD and light are working fine, the front LED flickers though! The model of the oven is IKEA Framdit OV9. One of the elements has 30 ohm resistance and the other has 60, and given the data on the elements they have 1650 and 800 Watts power rating respectively. So for 230v they resistance seems be fine.

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  • \$\begingroup\$ Honestly, just from looking at it, I would say it's almost certainly some kind of physical damage while shipping or something, or someone took a hammer to it or something. It seems a bit hard to believe that thermal expansion alone would cause this extreme warping, but I suppose it is possible. \$\endgroup\$ – Hearth May 22 at 15:33
  • \$\begingroup\$ It could well be that the element was hit by the oven tray while it was hot!? \$\endgroup\$ – Haider May 23 at 19:42
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It is shorted to case, check resistance between contact and outer metallic shield. This resistance should be infinite, in your case is something near zero if you test it with megger. You should change the damaged heater.

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  • \$\begingroup\$ I checked the if there is a short between the element cover and the terminals but couldn’t find anything wrong! \$\endgroup\$ – Haider May 22 at 9:11
  • \$\begingroup\$ @Haider You probaby have a "partial short". You need a Megger or similar to test it. Worst case it's fine even then at room temperature but with the heat expansion, it shorts and trips your breaker. Replace the heater! \$\endgroup\$ – winny May 22 at 9:14
  • \$\begingroup\$ Thanks, I’ve already ordered a new one. Will update the question and confirm the answer once it get it and try it out. \$\endgroup\$ – Haider May 22 at 9:20
  • \$\begingroup\$ @winny has right., as written in answer you may not be able to detect this short with an ordinary multimeter, as it uses a small voltage to check resistance. A megger sends a HV pulse which has the energy limit not to kill, but better not to touch wires when it energises So this HV pulse then detects the insulation break, while a multimeter can't. \$\endgroup\$ – Marko Buršič May 22 at 9:26
  • \$\begingroup\$ You may have to heat it to cherry red for the short to appear. At that temperature it's pretty soft and easy to deform. Fortunately they are easily available and pretty cheap for most ovens. If Ikea don't carry spares just google the oven name + "oven heating element" \$\endgroup\$ – Brian Drummond May 22 at 10:59
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What can cause a heating element to deform this way?

Bad mounting.

Metal expands when it gets hot. This means that this ~2 Meter heating strip becomes ~25mm longer per 100 degree rise in temperature.

When you have a steel tube fixed in two points and make it longer by heating it, something must give. Either the mounting must allow the expansion or the tube will bend.


These steel tubes contain heat conducting ceramic sand an a resistive wire for that carries the heating current. This wire is coiled to allow for bending and expansion.
However, when the bending radius is too tight, or a thermal cycling pumping effect moves the sand away, you will get a short circuit.

However, since everything expands and contracts by heat the short may not become noticeable until the heater gets to a certain temperature.

When designing mounting for heaters like this there may only be one rigid point. All other mounts must allow for sliding or other movement to give room to the expansion. (the clicking noises in your oven)

The reason for this element to fail is probably the horizontal mounting bar in the middle. It provided too much rigidity causing the element to buckle.

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  • \$\begingroup\$ fascinating! Even the humble heating element needs precision design. Thanks. \$\endgroup\$ – Haider May 22 at 12:42

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