Oven element failure

[brian_mk]

I have an electric oven - now many years old.
I have replaced the main circular 2.5kW oven element (ELEHY6708) several times over the years.
Another failure happened just a couple of days ago.

Soon after switching on, I noticed an unusual crackling noise from the oven.
When I opened the oven door I was alarmed to see a bright orange glow and smoke coming from the rear of the oven.
Previous failures were never that spectacular - the element usually just fails open circuit at power on.

The photo below shows the state of the element after I removed it.
Part of the element appears covered in molten metal.

I suspect the insulation broke down in such a way that the internal heater wire made contact with the earthed outer sheath.
If this happened part way round the coil, then the current to ground may have been insufficient to blow the cooker fuse in the main fuse box.
Hence the element continued to pass excessive current for some time, becoming so hot that it glowed orange.
This is worrying - potentially it could have resulted in a fire.
The house was built in 1985 and still has old fashioned wire fuses and no RCB.
If it was a partial short to ground then an RCB would have cut the power.
I think it may be time to get an RCB fitted and maybe replace the original fuse box with something more up to date.

There is a hot air circulating fan in the centre of the element. That is has an over temperature limit switch bolted on to the body.
I believe these are intended to protect against thermostat failures.
The limit switch did not operate in this case - probably because I cut the power before it reached its over-temperature threshold.

Has anyone else experienced a similar element failure?

 

[James]

Seen that type of failure many times.

often it is spray oven cleaner used, goes through the fan intake and then drips off the fan onto the bottom of the element. It is very caustic and breaks down the thin steel tube of the element and exposes the internals to moisture and anything else sucked in by the fan

 

[brian_mk]

Seen that type of failure many times.

often it is spray oven cleaner used, goes through the fan intake and then drips off the fan onto the bottom of the element. It is very caustic and breaks down the thin steel tube of the element and exposes the internals to moisture and anything else sucked in by the fan

I have never used spray cleaner on the oven in 35 years!

 

[littlespark]

Spray? Cleaner?

C… L….E…..A…..N….E….R…..???

No, Sorry. Don’t know what you’re on about.

 

[James]

Spray? Cleaner?

C… L….E…..A…..N….E….R…..???

No, Sorry. Don’t know what you’re on about.

Many men out there would say ASK THE WIFE.

however in our home we are far more politically correct than that, If I were to ask the wife to clean the oven because i thought it looked a bit dirty.

first would come "the look"

second would come some comment along the lines of "go ducking clean it yourself if you think I don't keep the house clean enough"

Finally would come some sort of suggestion that until the oven and kitchen is up to a much higher standard of cleanliness I will be eating nothing but humble pie and the only thing going in her mouth will be food ordered and paid for by me.

 

[littlespark]

Many men out there would say ASK THE WIFE.

however in our home we are far more politically correct than that, If I were to ask the wife to clean the oven because i thought it looked a bit dirty.

first would come "the look"

second would come some comment along the lines of "go ducking clean it yourself if you think I don't keep the house clean enough"

Finally would come some sort of suggestion that until the oven and kitchen is up to a much higher standard of cleanliness I will be eating nothing but humble pie and the only thing going in her mouth will be food ordered and paid for by me.

Of course my comment was purely in jest.

My wife and I have a very traditional set up at home. She cooks, cleans, shops, etc... I do the garden, car, DIY type stuff.
Nothing against the "politically correct" - those who might alternatively do those jobs, but this way works for us, and always has.

 

[James]

Don’t panic, mine was supposed to be taken light hearted too!
but if i really annoyed her, I might be going without something!

 

[brian_mk]

I was hoping for a somewhat more intelligent and helpful response.

The GE Appliances website says this:-

====

Sometime during the life of a range or wall oven a failure of the oven Bake or Broil elements could occur. When an element fails it will usually "open" the electrical circuit and no further heating will take place. When this happens, the element simply appears to have stopped working.In some rare instances the element will "short-out" against the sheath which is the outer visible part of the surface unit. This will cause the sheath to rupture and sparks may occur for a few seconds. At this point, one of two situations may result:

The household fuses or circuit breakers may "blow" or trip.
The surface unit will stop working. The sparking ceases after a few seconds. There may also be a "burning plastic" odor at this time.
We recommend that you not use the oven if the bake or broil element fails. Failure of one or both oven elements will not affect the surface burners. You may continue using these burners as needed.

No danger exists, even though service may now be required.
====

Personally, I am not convinced by the 'No Danger Exists' statement at the end.

It seems to me that it's about time the crude on/off oven thermostat was replaced with a solid state proportional control system (using a Triac or whatever). Such a system could easily incorporate a soft start that would increase the life of the element by reducing the thermal shock when 2.5kW of power is suddenly applied. It would also give a more even temperature control.

 

[brian_mk]

Ubelievable!
The replacement element I ordered has the same part number BUT they have changed the fixing stud centres from 56mm to 60mm so it doesn't fit! The 56mm parts are no longer available.

It means I now have to drill out the studs and replace them with bolts (using new holes or slots) or create new holes or slots in the oven back or buy a new oven.
I can think of no good reason why they would need to change the fixing dimensions.

 

[nicebutdim]

I can think of no good reason why they would need to change the fixing dimensions.

Perhaps it's no longer economically viable to produce elements for this oven and they decided to supply something that would work with slight modification.