New Oven tripping mcb massively

[Misterbarlow]

Hi everyone, stumbled across your forum while googling tonight, hoping for a bit of advice...
I have some electrical knowledge, and I fit/change electric meters for a living for past 20yrs for one of the big six!

Have been given a brand new (but faulty) oven by a relative, an Electrolux EOB3400EAX.
They got it brand new, don't know from where, cant find it on many websites, must have got it online??

The person who gave it to me said they got few days before Christmas and hadn't used it, as it was tripping out their electric from the off, and they were worrying about Christmas lunch failing etc as had lot of family coming over, they just thought it was too much for their wiring or mcb, so they just got another oven for Christmas which worked ok, and so this one been sat in the garage, and easy come for some, they couldn't be bothered sending it back so they asked if I wanted??

My prev oven been in use about 8yrs, no issues, wiring all good and up to scratch here..

So. wired it up, turned on, all seemed ok, turned the dual element oven on, was on about an hour or so to burn off factory residues & smells etc, all looking good, nice and hot working fine...

Went to rotate knob to grill to burn that off, and as I moved it one click there was massive pop and a flashover from the consumer unit area, and the mcb (40A dedicated cooker circuit, nothing else on it except ceramic hob [which was off]) had operated, the RCD did not operate.

I rotated control knob back to O position and tried to reset the mcb, but again a huge pop & flashover right in my face, we are talking sparks flying out of the mcb all over the floor, major flashing..

In the end I could only reset the mcb by switching off the cooker switch on the wall, but as soon as I pushed it back down, POP and sparks flying everywhere again...

So I have swapped back for now and old one working fine again, and checked inside cons unit and everything is good and tight...

I took the back and top off the oven and had a good poke about, and all seems visibly ok, no loose wires or spades etc, no black marks anywhere..

Just wondering if anyone has any advice on how to start fault finding, be shame not to use it, its a brand new £300 oven...
I assume its likely either one of the elements or the control knob??
How do I test the elements?

Thanks..

 

[SparkyChick]

Looking at the two ends of that element with the blackening... the one which is black appears to be slightly longer than the other. Is there any blackening on the rear panel? I'm thinking manufacturing tolerances not good enough and it's shorted out to the case.

 

[DPG]

Whatever it is you need to be sure that you have found it - otherwise you risk it happening again.

 

[johnduffell]

Yes my money is on casing as well.

We bought a "seconds" oven cheap that was all dented on the external panels, goodness knows how looked like a fight with a fork lift.

I took all the flimsy back and bottom panels off and straightened as best I could and inspected before powering the thing up for the first time. Inside was very similar to yours apart from without the blackening in my case.

 

[Misterbarlow]

Good call JohnDuffell, just looked and didn't realise the back case is dented, looked on the inside and bingo!!

Bit of hammer work later and might wrap the blades in tape for extra, and I reckon it should be good to go...

 

[DPG]

Nice one!
I'd still consider replacing that MCB as well though. It's been closed on to a direct short several times now, and it sounds like it hasn't fared too well.

 

[Misterbarlow]

Ok DPG, thanks for advice!!

 

[johnduffell]

Good call JohnDuffell, just looked and didn't realise the back case is dented, looked on the inside and bingo!!

Thanks although @SparkyChick said it first! Glad you're hopefully going to get a working oven out of it.

 

[Misterbarlow]

Thanks Sparkychick as well...

I beat the back panel out and stuck some 3M sticky back mastic strips we use in work for making safe exposed cutouts etc over the inside of the back panel around the burn marks to extra insulate it...

Put it back in last night.. no tripping, ran on every setting for half hour all seems fine, except one oddity??
When set to LIGHT only, which in manual says
"For a light with NO cooking function"
The grill element comes on & off if I turn the temp dial...!!

Any ideas??

 

[telectrix]

i had similar with a new element fitted in our 20 year old oven.replaced the spade connectors with the right angle insulated type.