Cooker fault tripped sockets??!??

[Greenie9657]

Hi everyone,

Just had a call from a relative to say cooker had blown so I nipped up there to find all the kitchen sockets had tripped as well.

Turn cooker off on the unit and isolate on the wall switch, turn everything back on at the CU and fine. The minute you switch the cooker isolator on, the cooker MCB trips as well as the downstairs sockets.
That's never right.

I thought the cooker problem could just be a blown element but I'm thinking they may be a bigger issue.

 

[JohnW2]

Turn cooker off on the unit and isolate on the wall switch, turn everything back on at the CU and fine. The minute you switch the cooker isolator on, the cooker MCB trips as well as the downstairs sockets. That's never right.

As you say, IF they are MCBs that certainly wouldn't be right - and would be worrying, because it presumably would imply some unintended connection between the two circuits. However, if they were RCBOs, rather than MCBs, then it's just possible (although, I would say, unlikely) that what you describe could happen with an N-E fault in the cooker.

Kind Regards, John

 

[Greenie9657]

Thanks john. I never took any notice if they were RCBOs. If anything the cooker might be but I would have thought the sockets weren't . I did notice RCDs but not 100% as I didn't have much time.
I'll have a look when I get back and post again.

 

[JohnW2]

Thanks john. I never took any notice if they were RCBOs. If anything the cooker might be but I would have thought the sockets weren't . I did notice RCDs but not 100% as I didn't have much time. I'll have a look when I get back and post again.

Fair enough. If there are RCDs, it is probably fairly unlikely that either cooker or sockets circuits would be on RCBOs. Distinguishing between MCBs and RCBs is obviously easy - just look for a 'test' button!

If they are MCBs, then I think some serious testing/investigation may be required, in which case an electrician will probably be needed.

Kind Regards, John

 

[sparkwright]

Are you sure both the cooker MCB and the sockets MCB aren't both protected by an RCD (RCCB)?

If so, I would expect the RCCB to trip, thus knocking out all circuits connected to it.

 

[JohnW2]

Are you sure both the cooker MCB and the sockets MCB aren't both protected by an RCD (RCCB)? ... If so, I would expect the RCCB to trip, thus knocking out all circuits connected to it.

That clearly would be a simple explanation, but the OP seems very clear in what he has told us - that two MCBs tripped but, although acknowledging the presence of RCDs, he said nothing about an RCD tripping.

Kind Regards, John

 

[Taylortwocities]

This may help you get the terminology right.
It will help get you the right assistance.

Untitled

• Taylortwocities
• 27 Mar 2010
• 43

 

[JohnW2]

This may help you get the terminology right. It will help get you the right assistance.

Indeed. As I said, in terms of what is visible when the CU's cover is on, it's the presence/absence of the test button which is the most obvious way (other than reading!) of distinguishing between an MCB and an RCBO.

Kind Regards, John

 

[Greenie9657]

Definate MCBs. Seperated CUs as well

 

[JohnW2]

Definate MCBs. Seperated CUs as well

Do you mean 'separated RCDs' (i.e. two blocks of MCBs, each protected by their own RCD)? If so, is the downstairs sockets circuit on a different RCD from the cooker circuit?

Do I take it from what you've said that no RCD has tripped at any time - just the two MCBs?

Kind Regards, John

 

[Greenie9657]

Definate MCBs. Seperated CUs as well

Do you mean 'separated RCDs' (i.e. two blocks of MCBs, each protected by their own RCD)? If so, is the downstairs sockets circuit on a different RCD from the cooker circuit?

Do I take it from what you've said that no RCD has tripped at any time - just the two MCBs?

Kind Regards, John

No. Seperated CUs. I've found the snag. I'll update later on.

 

[JohnW2]

No. Seperated CUs. I've found the snag. I'll update later on.

Oh - that's rather intriguing - I wait with bated breath for the update!

Kind Regards, John

 

[Greenie9657]

Right, well I'm still alive!

To clear up the separate CUs. One is the original and when they had an extension a second CU was added and this newer one is where the cooker is and the sockets are still on the old one.

Anyway, I visually checked the element on the cooker and it looked fine. Usually when they go you get some sort of visual indication whether it's a hole, scorch etc. so I pulled the oven out and opened the plastic box on the back where the terminals are and found the live was serverly burnt. That bottom pic shows the joined wires I couldn't pull them apart!

On closer inspection, I found the neutral had welded itself to the live. So I took it off, snipped it back as luckily there were enough slack on the cable, and re-did the wires and this time I sleeved the earth as there wasn't anything on it before.

Oven works fine. It just so happens that this day, 10 years after the cooker was installed, the insulation finally gave way probable chaffing I guess.

Before I reconnected the cooker I switched the sockets on and volt checked the red and black. 0v. I then switched the cooker on at the CU and 240v was there. Bingo!

The only reason I thought for the down stairs sockets going was there is a cable behind the oven, near this box that is fed from a fuse spur of the ring main, to power the cooker hood. But it's weird that the fuse didn't go in the FCU, just the MCB. You can see the cable going across the wall in the bottom photo.

Hope it all makes sense. A little bizarre!

Untitled

• Greenie9657
• 14 Sep 2014
• 1

Untitled

• Greenie9657
• 14 Sep 2014
• 1

 

[pineapple]

This is weird.
I've just come on here to post the same thing.
All the power in the house went off. Reset it and the cooker switch stayed down. If I try to reset that one all the power trips again.
It wasn't as if the cooker was on at the time.
Not competent around wiring so an electrician will be needed.
Wonder if it has anything to with yesterday when I spilled a load of liquid on the hob? Could it have got to some wiring?
Don't know whether I need a cooker repair or an electrician.

 

[Greenie9657]

This is weird.
I've just come on here to post the same thing.
All the power in the house went off. Reset it and the cooker switch stayed down. If I try to reset that one all the power trips again.
It wasn't as if the cooker was on at the time.
Not competent around wiring so an electrician will be needed.
Wonder if it has anything to with yesterday when I spilled a load of liquid on the hob? Could it have got to some wiring?[/b]

That is weird. But I wouldn't keep flicking the MCB back on. There's probably a spectacular flash if it's the same problem as me. Just make sure your CU is off and take a look. But if you aren't good around electric, you are right, I'd get someone in!