New electric cooker causing power to trip at fuse. The fuse is reluctant to flick back on after.

[Stephen]

Hi all.

Thank you all in advance for your help and advice.

I was hoping to get some help and advice on a cooker issue I'm experiencing.

My cooker is "brand new" and I recently had it installed by my father inlaw (competent tradesman although not an electrician)

The cooker is brand new but actually 3 years old... this is because it's an ex display oven from a hardware store (wife works there)

The Cooker will work fine for 20 uses. No issues whatsoever.

But we have had 4 occasions where we haven't been able to use it.

What was happening was we would turn the cooker on and it would trip 10 seconds later. Then we would put power back on then try again and it would trip 4 or 5 times before we sack it off for beans on toast.

We were not using the hob at the same time.

I will also add that when it happened last time the fuse wouldn't come back on. In fact most.times It trips for this reason I have to flick the fuse up multiple times.... that's another point it doesn't trip the rcd it trips everything at the fuse

I found one website that suggested the fuse not wanting to come back on can suggest an earth fault.

I was thinking maybe the wiring came loose in the back of the oven or the sockets maybe.

It can't be the element cause it will work for 20 times on full load with not a single issue and the fact it's brand new really.

I can't see it being an element issue but I'm hoping a knowlegable electrician may have an idea or a way to eliminate possibilities.

The key points are

• I can use the cooker most of the time
• It mostly trips immediately but can be 90 seconds after powering up
• I am not running anything at the same time
• The power trips to the whole house but the fuse board where it is on a separate fuse remains in the "on" position when it trips the electricity.
• When I try and flick the power back on at the fuse I sometimes have to do it 6 or 7 times for it to actually come back on.
• The old cooker never did this so the mains wiring can't be faulty surely.

I really appreciate any help. I am able to use it now but I did trip the power when I first turned it on tonight.

Thank you all in advance and apologies of this isn't the right forum.

Cooker is an AEG competence double oven.

Stephen

 

['mr2'gd4u]

I would say poorly installed the most likely culprit but without actually being there. .

Is it just me or is the edge of that double socket sitting on top of the 45A DP Switch?

Nope it's not just you..

 

[GBDamo]

To clarify, that Crabtree RCD may no longer be required, only a site visit will say for sure. It may be possible to remove or change to a 100mA, again a site visit will be required.

The RCD on the cooker side of your consumer unit should be tripping first but as the two are of the same sensitivity it's a guessing game as to which will trip.

This does not resolve the fault but will stop the whole house going down when a fault occurs.

The fault is likely to be with the oven, and more prcicely an element within it. These elements will absorb moisture if left used in damp conditions. This can be tested to prove and can be resolved by drying out through use..

Unfortunately until it dries out it will continue to trip your hole house to to the upfront RCD.

 

[SJD]

The two switches are probably a bit wider than a standard accessory plate, and the back box is a twin-1-gang, rather than two separate 1-gangs spaced apart. Hence something has to sit on top of something else!

 

[Deleted member 9648]

You need to have ALL circuits IR tested by an electrician, the cooker may be a red herring as if there is a N-E fault anywhere on your installation this can cause tripping only when a heavy load (such as your cooker) is on, misleading the uninitiated to assume the cooker is at fault. Of course it could be the cooker, but I recently attended a tripping fault where a perfectly good shower had been replaced because it only tripped when the shower was on.....and continued to trip when the new shower was used. Fault was on an outside light.

 

[Stephen]

Is it just me or is the edge of that double socket sitting on top of the 45A DP Switch?

It isn't you. Design flaw to be rectified by tiler in coming days.... knew it wasn't ideal... but is it a big risk.... apologies for my naivety

 

[Stephen]

The two switches are probably a bit wider than a standard accessory plate, and the back box is a twin-1-gang, rather than two separate 1-gangs spaced apart. Hence something has to sit on top of something else!

Don't know what this means sadly but.... all I know is it was an oversight when we put patress boxes in

 

[Toneyz]

As post 20. You need an electrician to do an insulation resistance test. There could be a fault on one of the other circuits. Out of interest what was the power/current rating of the old oven?

 

['mr2'gd4u]

Don't know what this means sadly but.... all I know is it was an oversight when we put patress boxes in

So you've recently had work done... Anything involving the cooker circuit other than connecting cooker?

 

[Stephen]

As post 20. You need an electrician to do an insulation resistance test. There could be a fault on one of the other circuits. Out of interest what was the power/current rating of the old oven?

Hi pal. Sadly I don't know. Looks like an electrician is the way forward.

 

[Marcus Vaughan]

When you say ‘flick the fuse up’ I think you are referring to the Crabtree Unit between the meter and the consumer unit.

If so - that is also an RCD - not sure why it is there though, as the circuits in the photo are protected by the RCD in the consumer unit.

Maybe there are other circuits in the consumer unit that are labelled ‘non RCD protected’ and someone has put this Crabtree ‘upfront’ RCCB (RCD) in?

It’s not a great idea to have an upfront RCD - as you have found out - as one faulty appliace leaking to earth will take out the whole house.

I agree with others that you should call an electrician to test the circuit, check the connections at the cooker connection unit, check the wiring is of a
suitable size, check the RCD etc.

The same electrician may well be able to remove that upfront RCD as well, depending on what they find.

Maybe a stand off picture of the whole consumer unit?

 

[Stephen]

So you've recently had work done... Anything involving the cooker circuit other than connecting cooker?

Ok well there is something else. The old isolation switch before remodelling was a huge external patress box on the wall the other side of the kitchen.

In order to "extend" the existing wiring from that location to the new isolation sockets and then the cooker a large junction box was buried into the wall which was then plastered over.

 

[Stephen]

When you say ‘flick the fuse up’ I think you are referring to the Crabtree Unit between the meter and the consumer unit.

If so - that is also an RCD - not sure why it is there though, as the circuits in the photo are protected by the RCD in the consumer unit.

Maybe there are other circuits in the consumer unit that are labelled ‘non RCD protected’ and someone has put this Crabtree ‘upfront’ RCCB (RCD) in?

It’s not a great idea to have an upfront RCD - as you have found out - as one faulty appliace leaking to earth will take out the whole house.

I agree with others that you should call an electrician to test the circuit, check the connections at the cooker connection unit, check the wiring is of a
suitable size, check the RCD etc.

The same electrician may well be able to remove that upfront RCD as well, depending on what they find.

Maybe a stand off picture of the whole consumer unit?

 

[Stephen]

When you say ‘flick the fuse up’ I think you are referring to the Crabtree Unit between the meter and the consumer unit.

If so - that is also an RCD - not sure why it is there though, as the circuits in the photo are protected by the RCD in the consumer unit.

Maybe there are other circuits in the consumer unit that are labelled ‘non RCD protected’ and someone has put this Crabtree ‘upfront’ RCCB (RCD) in?

It’s not a great idea to have an upfront RCD - as you have found out - as one faulty appliace leaking to earth will take out the whole house.

I agree with others that you should call an electrician to test the circuit, check the connections at the cooker connection unit, check the wiring is of a
suitable size, check the RCD etc.

The same electrician may well be able to remove that upfront RCD as well, depending on what they find.

Maybe a stand off picture of the whole consumer unit?

And yes Marcus... that's what I thought was the fuse.... didn't know it was an RCD it's been there since prior to we bought the house.

 

[SJD]

Ok well there is something else. The old isolation switch before remodelling was a huge external patress box on the wall the other side of the kitchen.

In order to "extend" the existing wiring from that location to the new isolation sockets and then the cooker a large junction box was buried into the wall which was then plastered over.

Do you have a photo of this junction box, before it was plastered over (the insides, what connectors were used)?

 

['mr2'gd4u]

Ok well there is something else. The old isolation switch before remodelling was a huge external patress box on the wall the other side of the kitchen.

In order to "extend" the existing wiring from that location to the new isolation sockets and then the cooker a large junction box was buried into the wall which was then plastered over.

How was the connections in that junction box terminated? Screwed? MF?