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]

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.

 

['mr2'gd4u]

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

You disagree with MF connections when buried?

 

[SparkyChick]

I should add, if you wanted to get it regularised, you would need to discuss it with your LABC as some are fussy and only allow this kind of thing to be done by certain scheme members or certain companies.

 

[Stephen]

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.

Yeah ... sounds similar to my cooker.. the one we used was 30amp

Axiom Junction Box 30A 3 Terminal White - https://www.toolstation.com/shop/p28404

 

[SparkyChick]

You disagree with MF connections when buried?

Personally I disagree with anything buried in the wall if there is no indication at all that it's there. It's a disaster waiting to happen if there's cables floating around and no accessories to give even a hint they exist.

Jointing method doesn't come into it.

 

[123]

My father in law.

Very competent although admittedly not a trained electrician.

Thanks

I'll beg to differ on that. Burying 32A junction boxes in the wall is anything but good, it's downright shoddy. Chances are some cable is now no longer in safe zones either.

 

[123]

You disagree with MF connections when buried?

Yep, @SparkyChick in post #54 covers why. Plus most MF JB's are not designed to be plastered over, something like a resin joint might be but just who does that in a kitchen.

 

[Stephen]

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

Axiom Junction Box 30A 3 Terminal White - https://www.toolstation.com/shop/p28404

Was this connection box.

Was cooker cable joined inside with screws.

 

[GBDamo]

Axiom Junction Box 30A 3 Terminal White - https://www.toolstation.com/shop/p28404

Was this connection box.

Was cooker cable joined inside with screws.

This isn't getting better.

 

[123]

Axiom Junction Box 30A 3 Terminal White - https://www.toolstation.com/shop/p28404

Was this connection box.

Was cooker cable joined inside with screws.

I'm assuming the cooker cable comes from the ceiling down to this, has it now moved to the left or right, with this junction box and cable plastered and tiled over?

 

[GBDamo]

We've all seen this done before, I think, but it dont make it correct, not just for the reasons already mentioned.

It's one of those things that could be fine and last years but now the OP has a fault these are the things you really wish you hadn't done.

It can be proved that this junction is not the cause of the fault, if that's the case, but it will never be correct and it will always be a potential hazard.