Help needed - Cooker tripping house electrics when in standby mode

[PaulP]

We recently purchased a new freestanding cooker from John Lewis. An AEG 49332i-MN with Induction hob which my wife was delighted with!
The cooker is hardwired direct to a Crabtree consumer unit with a main RCCB 80A 30mA – Via a B40 MCB switch, cooker switch on the wall to junction box behind cooker then to cooker. The house is 16 years old and the old cooker never used to trip the electrics.
Straight from day one our electrics ‘tripped out’ randomly 2 to 3 times a day ONLY IN STANDBY MODE with no elements turn on whatsoever JUST THE CLOCK illuminated and working. It will trip at 2am in the morning when we’re all tucked up in bed.
We had John Lewis cooker repair man out to check the possible faulty cooker.
He found NOTHING WRONG with the cooker and said that when the cooker is in standby the clock does not use/require an earth on the circuit board at that stage.
He suggested replacing the wall cooker switch – which I did – It didn’t help, the electrics still tripped out. So I bypassed the junction box at the back of cooker – still didn’t help. I then wired the cooker straight to the consumer unit and replaced the cooker MCB with a new one. That didn’t help.
The electrics have NOT tripped at all when the cooker is NOT connected and NOT in standby. And have not tripped when we actually use the cooker whether it’s the hob or the ovens. It has tripped a few times when I have turned it off at the wall after cooking tea but 99% of the time is when it’s in standby mode.
So 2 weeks later, it was finally swapped for a new cooker. Problem solved we thought – it lasted about a day and a half and it tripped again!
Does anyone have any idea what’s causing this? My wife loves this cooker but turning it off at the wall and not using the timer is not really an option with a new cooker. Any ideas as to solving this issue would be gladly appreciated.
I also want to say that John Lewis have been brilliant about this and can only praise their after-sales service.
link to cooker is here

 

[Marvo]

We had John Lewis cooker repair man out to check the possible faulty cooker.
He found NOTHING WRONG with the cooker and said that when the cooker is in standby the clock does not use/require an earth on the circuit board at that stage.

This is a bit confusing, maybe you're misquoting or you misunderstood him or the other option is he's an idiot and is talking rubbish. Did he disconnect the earth by any chance?

He suggested replacing the wall cooker switch – which I did – It didn’t help, the electrics still tripped out.

The concept of electrical fault finding is that you use test equipment to localise the fault then when you've narrowed it down to a single item or component you repair or replace it. Did his test results prove the isolator was a problem or was this just a guess?

So I bypassed the junction box at the back of cooker – still didn’t help. I then wired the cooker straight to the consumer unit and replaced the cooker MCB with a new one. That didn’t help.

There's two problems with replacing and bypassing stuff willy-nilly, firstly it can end up being expensive because you wind up replacing a bunch of stuff that was never the problem in the first place. Secondly you are likely to treat the symptoms of the fault without remedying the actual cause.

The electrics have NOT tripped at all when the cooker is NOT connected and NOT in standby. And have not tripped when we actually use the cooker whether it’s the hob or the ovens. It has tripped a few times when I have turned it off at the wall after cooking tea but 99% of the time is when it’s in standby mode.

Does it trip at the exact moment you switch it off at the wall or does it trip later on whilst it's still switched off at the wall?

So 2 weeks later, it was finally swapped for a new cooker. Problem solved we thought – it lasted about a day and a half and it tripped again!
Does anyone have any idea what’s causing this? My wife loves this cooker but turning it off at the wall and not using the timer is not really an option with a new cooker. Any ideas as to solving this issue would be gladly appreciated.
I also want to say that John Lewis have been brilliant about this and can only praise their after-sales service.
link to cooker is here

Up until this point in your post there was strong circumstantial evidence that the cooker itself was the problem but if it still happens with a replacement cooker then either there's a manufacture fault with a large batch of cookers (fairly unlikely but not unheard of) or there's something else contributing to the problem.

With earth leakage faults the RCD in the consumer unit sees the cumulative leakage from all the circuits that are connected to it. This means that several small leakage faults that might be acceptable in isolation all add up together to an amount of leakage that causes a tripping fault.

To find earth leakage faults and to test the RCD in the consumer unit you need special test equipment which is outside of the realms of most homeowners so to be honest I'd suggest it's time to find an experienced electrician who's got the right test equipment and the knowledge to use it. I'd imagine it would take an hour or less to find the fault(s) and test the operation RCD and then whatever time is needed on top of that to make repairs so it shouldn't cost a fortune and it will give you peace of mind your electrical installation is safe and operating correctly.

 

[markc123]

We recently purchased a new freestanding cooker from John Lewis. An AEG 49332i-MN with Induction hob which my wife was delighted with!
The cooker is hardwired direct to a Crabtree consumer unit with a main RCCB 80A 30mA – Via a B40 MCB switch, cooker switch on the wall to junction box behind cooker then to cooker. The house is 16 years old and the old cooker never used to trip the electrics.
Straight from day one our electrics ‘tripped out’ randomly 2 to 3 times a day ONLY IN STANDBY MODE with no elements turn on whatsoever JUST THE CLOCK illuminated and working. It will trip at 2am in the morning when we’re all tucked up in bed.This happening when you press the ignition by any chance? Could be the tranny for the ignitor.
We had John Lewis cooker repair man out to check the possible faulty cooker.
He found NOTHING WRONG with the cooker and said that when the cooker is in standby the clock does not use/require an earth on the circuit board at that stage.Was he foreign?
He suggested replacing the wall cooker switch – which I did – It didn’t help, the electrics still tripped out. So I bypassed the junction box at the back of cooker – still didn’t help. I then wired the cooker straight to the consumer unit and replaced the cooker MCB with a new one. That didn’t help. This is where i start to detect a rat, appologies if not, but going to that extent...really? Did you move the cooker, or did you use a ridiculously long piece of cable?
The electrics have NOT tripped at all when the cooker is NOT connected and NOT in standby.Get Mr.John Lewis back And have not tripped when we actually use the cooker whether it’s the hob or the ovens. It has tripped a few times when I have turned it off at the wall after cooking tea but 99% of the time is when it’s in standby mode.Loose Connection ?
So 2 weeks later, it was finally swapped for a new cooker. Problem solved we thought – it lasted about a day and a half and it tripped again!
Does anyone have any idea what’s causing this? My wife loves this cooker but turning it off at the wall and not using the timer is not really an option with a new cooker. Any ideas as to solving this issue would be gladly appreciated.
I also want to say that John Lewis have been brilliant about this and can only praise their after-sales service.
link to cooker is here

This thread is confusing at best.

Is it tripping out the RCD or just the MCB ? I've heard of certain makes/types of Fridges/Fridge-Freezers that aren't compatiable with RCD'S .... never known it with a cooker, but that's not to say it won't be this.

Have you read the manufactures instructions and seen whether you maybe need a type C breaker instead of a B?

Disconnect the cooker and IR the cooker circuit, it'll soon tell you whether the problem is with the wiring or the cooker. Failing that, and i appreciate this is the DIY thread, you'll have to call out a sparks.

 

[Octopus]

Me thinks you need a competent spark with a MFT before you call John Lewis again!