neff oven tripping rcd changing temp

[dalboy]

hi all
need a bit of help!

i have a neff oven that has been working fine for 3 years. top oven all works fine.

bottom oven I can choose from fan grill etc with the dial but as soon as I change temp from 0 within a few seconds it trips the rcd.

I bought a new bottom element and still same issue. don' think there is anything wrong with old one as multimeter shows continuity.

took thing apart and even swapped thermo from top oven with bottom and still trips so must be a bottom wiring issue?

there are 4 wires coming from the bottom thermostat dial. process of elimination I removed each wire and flicked power back on. it only seemed to trip when the red and white lead was connected - I followed this lead and it goes to where the bottom element goes into a small unit which I'm not sure what it is. on the image it is near the top with the red and white lead going into it. I put multi meter on this unit and it seems to have continuity.

I did notice behind this area above, the back plate is burnt / marked

all cables looked attached properly and none were frayed but some look black from the above

just to add I done all the tests without the bottom element attached. as it was tripping with or without it. assume if it was the element and I removed it, it shouldn't trip?

please see images attached if they help

thanks in advance really appreciate

 

[Squid]

Have you tested the switch or at least taken it out of the equation?

 

[Andy5678]

Some cables wires look damaged/melted and could be making contact to the metal casing

 

[dalboy]

sorry what switch?

 

[dalboy]

Have you tested the switch or at least taken it out of the equation?

sorry what switch?

 

[dalboy]

Some cables wires look damaged/melted and could be making contact to the metal casing

thanks

I tried with the metal panel off and it still tripped

not that great with electrics but can I test each wire with the multi meter? just run one contact to the end of the wire and other contact to other end?

 

[Wilko]

just to add I done all the tests without the bottom element attached. as it was tripping with or without it. assume if it was the element and I removed it, it shouldn't trip?

Yes, that would be my thought too. Have you got a cooker isolation switch ? Please be very careful to disconnect the cooker before touching anything.
What has caused that mark on the panel shown in your 3rd pic?

 

[dalboy]

Yes, that would be my thought too. Have you got a cooker isolation switch ? Please be very careful to disconnect the cooker before touching anything.
What has caused that mark on the panel shown in your 3rd pic?

thanks

yes i isolated it via switch and turned whole house mains off.

i don't know what the mark is as never opened it up before as never had an issue. it doesn't look good and I am guessing it is to do with the trip issue

 

[123]

What is tripping, the MCB or the RCD?

To go around randomly replacing parts is a false economy.

Also to rely on a bang test as a method of fault finding is even worse. You will possibly cause more damage and potentially clear the fault but leave the oven in a very dangerous condition.

 

[dalboy]

What is tripping, the MCB or the RCD?

To go around randomly replacing parts is a false economy.

Also to rely on a bang test as a method of fault finding is even worse. You will possibly cause more damage and potentially clear the fault but leave the oven in a very dangerous condition.

hmm ok thabks

its labelled rcd on my fusebox

I only bought the element as most obvious thing to replace. it can be sent back

 

[Squid]

sorry what switch?

The one you call the "thermostat dial"

 

[Wilko]

The RCD trips because there is a connection to the cooker's earthed frame that shouldn't be there. This could be from a failure in the switch, wiring, temperature sensor, fan or element.
As a shot from left field, are there any other things that trip the RCD?

 

[dalboy]

The RCD trips because there is a connection to the cooker's earthed frame that shouldn't be there. This could be from a failure in the switch, wiring, temperature sensor, fan or element.
As a shot from left field, is there any other things that trip the RCD?

nope nothing

not sure where to go next without calling someone out

 

[dalboy]

The one you call the "thermostat dial"

oh ok.

how would i take it out the equation as I need it connected to turn the heat up and check the oven heats without tripping

I swapped the other thermostat that belongs to top oven with bottom wiring and it still tripped so it must be one of these 4 wires, no?

 

[dalboy]

bottom fan / light work too

 

[dalboy]

does anyone what that part is that is circled on the left? how would you test it to see if working?

 

[dalboy]

double post sorry

 

[dalboy]

is that the thermal cut out that I have circled in yellow to the left? could it be this? how would i check its properly working?

thanks all

 

[Squid]

As mentioned it could be leakage to earth, how old is the oven?

 

[Squid]

In the photo you posted I can see a copper winding, I believe that should have a cover on it, it also seems to line up with the burn marks on the panel.