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

 

[SparkyChick]

Could you post a picture of the consumer unit (fuse box/board), and explain what trips please?

 

[telectrix]

think this one needs a site visit.there's a few possibilities could be the problem.

 

[Pete999]

Agree with both Tel and SC

 

[Stephen]

Could you post a picture of the consumer unit (fuse box/board), and explain what trips please?

This is where it trips. Thanks for all your help

 

[Stephen]

Could you post a picture of the consumer unit (fuse box/board), and explain what trips please?

The kitchen spur rcd circuit switch remains 'on" at all times

 

[Fitzy]

Can you please tell us what the cookers wattage rating is and what the MCB rating is?

 

[Stephen]

Can you please tell us what the cookers wattage rating is and what the MCB rating is?

Will let you know asap

 

[Fitzy]

Do you know if there’s anything else on the kitchen spur circuit or is it exclusive to the cooker?

 

[GBDamo]

RCD roulette. 30mA up front alongside a 30mA in the CU.

Fault on the oven/wiring to the oven.

Could it be a damp element again?

 

[Stephen]

Can you please tell us what the cookers wattage rating is and what the MCB rating is?

5.9 kw max wattage. All other figures will be at the back.

 

[littlespark]

Earth fault. The 80A rccb is slightly more sensitive than the 63 in the CU even tho both are 30mA

An electrician will have test equipment to test the units, and the cooker.
Ex shelf display models can be a little glitchy just with sitting in a shop. Dust, damp etc.

 

[Stephen]

RCD roulette. 30mA up front alongside a 30mA in the CU.

Fault on the oven/wiring to the oven.

Could it be a damp element again?

You could be onto something here pal. Cooker was taken from a display kitchen 2 years ago. Been stored under the stairs since then. And was installed 1 month ago.

Understairs cupboard isn't exactly damp.... but it was there a while.

 

[Stephen]

Do you know if there’s anything else on the kitchen spur circuit or is it exclusive to the cooker?

Yes... hob is on it too

 

[123]

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

 

['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?

 

[Deleted member 9648]

It's a TT, the upfront RCD is a relic of the previous DB

 

[SparkyChick]

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.

Who did the kitchen wiring? Did you get a certificate for it?

Can you remember where that junction box is?

 

[Stephen]

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.

I will add we use a power shower which doesnt cause this to trip.... what would prevent this Crabtree rcd from flicking back on?

As I discussed in my OP when it trips this RCD is reluctant to trip back on.... takes sometimes 8 or more attempts. Wondered if you knew?

 

[Stephen]

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.

I will add we use a power shower which doesnt cause this to trip.... what would prevent this Crabtree rcd from flicking back on?

As I discussed in my OP when it trips this RCD is reluctant to trip back on.... takes sometimes 8 or more attempts. Wondered if you knew?

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

Yes screwed... it was a large round junction box... I can find a url for it from toolstation if needed?

 

[Deleted member 9648]

I will add we use a power shower which doesnt cause this to trip.... what would prevent this Crabtree rcd from flicking back on?

As I discussed in my OP when it trips this RCD is reluctant to trip back on.... takes sometimes 8 or more attempts. Wondered if you knew?

A power shower is a relatively light load compared to a cooker, it's sounding more and more like a N-E fault, not necessarily on the cooker

 

[SparkyChick]

I will add we use a power shower which doesnt cause this to trip.... what would prevent this Crabtree rcd from flicking back on?

As I discussed in my OP when it trips this RCD is reluctant to trip back on.... takes sometimes 8 or more attempts. Wondered if you knew?

When it trips, do you leave everything on and just turn it back on?

If so, the next time it trips, turn everything off in the fuse box except the RCDs, turn the big RCD that trips back on and then turn them back on one at a time... do the cooker last.

It's possible the fault is in the element and as it cools down it goes away and allows you to reset the RCD, but following this procedure above should (if the fault is only on the cooker) allow you to get the power back on quicker.

You shouldn't really keep turning it on under load either as it will damage the contacts.

 

[Stephen]

Who did the kitchen wiring? Did you get a certificate for it?

Can you remember where that junction box is?

No other wiring was touched.... just extended original installation so we can move the isolation sockets.

I can remember where the junction box is buried but has been freshly decorated over.

 

[Stephen]

Who did the kitchen wiring? Did you get a certificate for it?

Can you remember where that junction box is?

And no certificate

 

[SparkyChick]

No other wiring was touched.... just extended original installation so we can move the isolation sockets.

I can remember where the junction box is buried but has been freshly decorated over.

Well I hate to break it to you, but you may need to do a bit of touching up as the fault could be in there.

You're going to need the assistance of a local spark with appropriate test gear I think.

 

['mr2'gd4u]

I will add we use a power shower which doesnt cause this to trip.... what would prevent this Crabtree rcd from flicking back on?

As I discussed in my OP when it trips this RCD is reluctant to trip back on.... takes sometimes 8 or more attempts. Wondered if you knew?

Yes screwed... it was a large round junction box... I can find a url for it from toolstation if needed?

If if buried 8t needs to be maintainence free.

 

[Stephen]

When it trips, do you leave everything on and just turn it back on?

If so, the next time it trips, turn everything off in the fuse box except the RCDs, turn the big RCD that trips back on and then turn them back on one at a time... do the cooker last.

It's possible the fault is in the element and as it cools down it goes away and allows you to reset the RCD, but following this procedure above should (if the fault is only on the cooker) allow you to get the power back on quicker.

You shouldn't really keep turning it on under load either as it will damage the contacts.

I will do that and I agree it isn't ideal.

The cooker rarely gets up to temperature when it trips.

Also I have used the cooker for 10 days with no trips.... seems sporadic.

 

[SparkyChick]

I will do that and I agree it isn't ideal.

The cooker rarely gets up to temperature when it trips.

Also I have used the cooker for 10 days with no trips.... seems sporadic.

It's not just faults that can trip RCDs. It could be cumulative leakage, where under a certain set of circumstances there is over 30mA of leakage, could be sometimes there is leakage in the junction box and others not.

Loose connections can also trip RCDs.

 

[123]

Out of interest, who did the works to extend the cooker circuit and put that junction box in the wall?

 

[Stephen]

It's a TT, the upfront RCD is a relic of the previous DB

Hi what do you mean my this please? I tried googling the acronyms to no joy. Appreciate your help

 

[Stephen]

Out of interest, who did the works to extend the cooker circuit and put that junction box in the wall?

My father in law.

Very competent although admittedly not a trained electrician.

Thanks

 

[SparkyChick]

Hi what do you mean my this please? I tried googling the acronyms to no joy. Appreciate your help

TT is an earthing system, you'll have an earth rod (the cable that disappears through the wall most likely). Because TT doesn't allow much current to flow under some fault conditions, RCDs were added upfront to improve safety.

Now you have RCDs in your consumer unit, it's not needed. If the CU was metal, we might install a 100mA time delayed RCD to protect the connections between the consumer unit and the meter, but for all intents and purposes you don't need it. It should have been removed when the consumer unit was upgraded.

 

['mr2'gd4u]

Hi what do you mean my this please? I tried googling the acronyms to no joy. Appreciate your help

Your setup has an earth spike in the ground, that's why there is no earth supplied by your dno.

 

[Stephen]

TT is an earthing system, you'll have an earth rod (the cable that disappears through the wall most likely). Because TT doesn't allow much current to flow under some fault conditions, RCDs were added upfront to improve safety.

Now you have RCDs in your consumer unit, it's not needed. If the CU was metal, we might install a 100mA time delayed RCD to protect the connections between the consumer unit and the meter, but for all intents and purposes you don't need it. It should have been removed when the consumer unit was upgraded.

Thank you so much for all your help.

Really appreciate all your help.

Thanks

 

[littlespark]

I’ve just seen exactly the same thing. Cooker supply cable jointed in the old 45A switch box and tiled over.
Joint made in a J401 spur box which I believe is only rated 30A
Luckily there was enough spare cable in attic to reroute and move to where it needed to be.
Also needed to rewire the rfc in kitchen where I found a spur off a spur off a spur off the rfc.

 

[SparkyChick]

Unfortunately in Wales, electrical work in your kitchen is covered under Part P of the building regulations. There should be at least a Minor Electrical Installation Works certificate and your local authority building control department should have been notified that the work has been carried out.

You're technically responsible for the notification or lack of.

It can be corrected, but you'd need to employee an electrician to carry out an Electrical Installation Condition Report and probably pay your LABC a fee to have the work regularised.