Help needed with hob fault

[Billythekid]

Just been to look at a hob that has been getting hot above the electrical / gas connections. I was unfortunately unable to locate the source of the problem.

No visible damage to cables,
Zs fine,
RCD checked out fine,
IR >999 @500v,
And is still fully operational.

I’m Baffled, any ideas?

 

[Leesparkykent]

Scrap it and get a new one.

 

[SparkyChick]

Did it actually get hot whilst you were there?

There looks to have been a sticker in that location... could have burned by something placed on it???

I wouldn't have thought that supply (assuming it's fused properly) would be able to deliver enough power to cause that.

 

[Pete999]

Just been to look at a hob that has been getting hot above the electrical / gas connections. I was unfortunately unable to locate the source of the problem.

No visible damage to cables,
Zs fine,
RCD checked out fine,
IR >999 @500v,
And is still fully operational.

I’m Baffled, any ideas?

View attachment 39282

View attachment 39283

View attachment 39284

Heat rises, hence anything above the heat source will receive a rise in temperature and get hot, simple physics in essence.

 

[Billythekid]

Yeah, they are going to buy a new one anyway, but I don’t like leaving without finding the cause. No damage anywhere other than under the sticker - I have a video of my nephew pouring a little water on it - and it boiled?

 

[SparkyChick]

I know you probably won't be able to answer these...

With the power off did it cool down?

With the gas off did it cool down? It's more over the gas inlet... is it possible there is a leak that has been ignited and is slowly cooking the cooker from the inside???

Really grasping for ideas I know

 

[Octopus]

Did you take it out and inspect the connections? Looks like a classic case of a loose connection to me

 

[Billythekid]

No sign of thermal damage underneath. I was also clutching at straws, just as I was leaving I remembered the oven had been removed and had a metal case that could’ve been touching the gas pipe, so I checked that too - all fine.

The picture doesn’t show the mark very well, but it looks like an arc welder has been used on the casing.

I was unable to replicate the fault - I turned the gas back on, used all the hobs. Installed the oven and put that on too.

Water bonded, gas bonded - all tests were as you’d expect them to be?

 

[Billythekid]

I know you probably won't be able to answer these...

With the power off did it cool down?

With the gas off did it cool down? It's more over the gas inlet... is it possible there is a leak that has been ignited and is slowly cooking the cooker from the inside???

Really grasping for ideas I know

They turned the gas and electricity off, and yes it cooled down - just cannot get it to heat up again now.

 

[Billythekid]

Did you take it out and inspect the connections? Looks like a classic case of a loose connection to me

Yeah, I checked underneath. I would’ve liked to have removed it but there is no isolation point for the gas.

 

[123]

Did you take it out and inspect the connections? Looks like a classic case of a loose connection to me

On a gas hob really?

It looks like a burnt sticker to me. Never the less, I've never seen a loose connection burn through stainless steel from the connection block below.

 

[telectrix]

bloody obvious to me. it's where an alien spacecraft landed, bearing in mind that it was from a planet where the inhabitants are only 2" tall by earth standards.

 

[Billythekid]

On a gas hob really?

It looks like a burnt sticker to me. Never the less, I've never seen a loose connection burn through stainless steel from the connection block below.

I’ve seen similar marks before but there has always been a logical explanation.

I was beginning to think of an external issue, but nothing else has been damaged - usually TV’s, boilers, programmers, etc are damaged too.

 

[Billythekid]

bloody obvious to me. it's where an alien spacecraft landed, bearing in mind that it was from a planet where the inhabitants are only 2" tall by earth standards.

More plausible than anything I can think of right now.

 

[Pete999]

bloody obvious to me. it's where an alien spacecraft landed, bearing in mind that it was from a planet where the inhabitants are only 2" tall by earth standards.

Wrong Tel, it's a Phaser burn, probably set on Stun

 

[Toneyz]

bloody obvious to me. it's where an alien spacecraft landed, bearing in mind that it was from a planet where the inhabitants are only 2" tall by earth standards.

How many cans have you had /you sure its tobacco in those smokes?

 

[snowhead]

I was unable to replicate the fault - I turned the gas back on, used all the hobs. Installed the oven and put that on too.

So despite there being an obvious problem on a GAS APPLIANCE you've left the hob and electric oven working?

You're Gassafe registered then?

 

[Billythekid]

There is no isolation for the gas other than the main isolation valve at the meter.

The Hob is being replaced by another person arranged with the landlord - I can only ensure that there is no immediate danger from the electrical side.

 

[marconi]

https://s3-eu-west-1.amazonaws.com/howdens-howden-prod/web_content/media/library/pdf/3168.pdf

On page 19 of this link one can see the mains connection for this hob. Is this directly underneath the hot spot you photographed?

If this is an electrical problem I wonder if the earth connection terminal for the hob is welded directly to the metalwork underneath the hotspot. If so, then perhaps a high current has flowed through this weld and terminal down the flex to the plug and thence to the RFC cpc back to the MET. If the current was high enough (and its square) and conductivity of the welded connection low significant Ohmic heating may have taken place.

For the location of the origin of such an earth fault current I would:

a. check the presence and conductivity of gas and water bonds back to the MET.

b. check the earthing and IR of electric showers, immersion heaters central heating system (which may have their metal water pipes connected to the gas pipes through the HW and CH system). It could be they have L-E or N-E faults which are being routed partly or in full through the gas pipe to the hob and then to its mains supply cpc.

c. the earthing system and it correctness ie: MET, earthing conductor, means of earth, TT, TNCS, TNS...

Just some musings for you to consider - you get the sense of what I mean.

 

[telectrix]

How many cans have you had /you sure its tobacco in those smokes?

don't do cans. they usually contain that fake beer called lager. one reason them germans lost 2 world wars. they hadn't got real ale to sustain them.