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?

 

[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.

 

[Wilko]

... the earthing system and it correctness ...

Very thought provoking, as usual @marconi !
I'm thinking if one could boil water off it and IR is ok then the fault is solid but not in that cook top.

 

[Toneyz]

If the hob is going to be replaced soon and the thought is the electrical supply disconnect and use hob lighter for the time being.

 

[DJ Ovengloves]

Is it possible that the main oven has a leak and venting hot fumes underneath?

 

[Squid]

Remove the plug and see if it still happens, if they are replacing it they can buy a lighter to ignite the gas.

 

[lurch]

Looks like the control knob is showing some signs of heat damage also