Cooker hood trips other circuits on fuse board: what's going on?

[telectrix]

you're correct, mid. serves me right for reading posts on phone. deleted my irrelevant post and going to drown myself. ( in beer, you numpty, not the canal )

 

[Midwest]

you're correct, mid. serves me right for reading posts on phone. deleted my irrelevant post and going to drown myself. ( in beer, you numpty, not the canal )

I dunno, I keep getting corrected all the time. I put it down to age, poor reading glasses and a lack of quaffable wine or refreshing beer.

 

[Pete999]

You appear to have RCBOs... these are a combination of MCB (miniature circuit breaker, which protects the cables of the installation against over current - preventing the cables from getting hot and potentially catching fire etc.) and an RCD (Residual current device, which detects current leaking from the circuit, typically through the earth and cuts the power when this leakage is above a predetermined level - for domestic use, this is typically 30mA).

Based on the fact that turning something on on one circuit trips two circuits, you could have a situation referred to as a borrowed neutral, when the neutral wire from one circuit is actually used for another circuit which has it's own live feed. In this case, the current flowing out of one RCBO won't be the same as is coming back into it (it will trip) and the current flowing into another won't be the same as is going out (it will also trip).

I'd also be looking to rule out a neutral-earth fault (where there is an unwanted connection between the neutral wire and the earth wire).

These two issues at least could cause two circuits to trip at the same time.

I'm assuming by the fact that you mention the kitchen has been worked on, the problems started after that? If not, when did they start and had you had anything done immediately before that?

Is this totally repeatable? i.e. does the fault occur every time you turn on the extractor?

You say you've had a number of electricians look at it. Were they all registered with competent persons schemes such as NICEIC, NAPIT? You can check here:- Home - http://www.electricalcompetentperson.co.uk/

I think others will agree when I say, you need to find yourself a decent spark. I'd start by taking a look at the member directory here.

Deleted

 

[Pete999]

Deleted

No I'll continue, just because you are not a member of the CPS doesn't make you a bad Electrician, sorry but that hit a nerve.

 

[Midwest]

OP from what you've described, your faulty (possibly) cooker hood is tripping circuits 5 or 6, when logic suggests it should be tripping circuit 4, i.e. kitchen sockets? Unless the kitchen fitter, pinched a supply from the upstairs ring to feed the cooker hood?

Think the sparking hob thing is artistic licence, and too much wine when cooking

You could unplug your cooker hood temporarily, and see if that stops the fault.

 

[PEG]

No I'll continue, just because you are not a member of the CPS doesn't make you a bad Electrician, sorry but that hit a nerve.

I agree,pete,but the converse is just as true,being registered to anything,does not give any guarantee of competence.

I regularly get asked to follow up on some weird fault,or other,and most likely,the previous investigators,have had splendid,liveried up wheels and togs

The OP mentioned that the property had been "mostly re-wired",but the two floors of sockets outlets going off at the same time,may be a concern.

 

[SparkyChick]

The posts that were made earlier in this thread have been lost due to the server move, I replied with this message.

No I'll continue, just because you are not a member of the CPS doesn't make you a bad Electrician, sorry but that hit a nerve.

I know it doesn't Pete and I can see the implication from my comment, sorry for that, but that's not what I meant. I know several great sparks who aren't members of the scams because they don't need to be, but for a householder it's a reasonably good place to start and I feel we should be encouraging householders to check people out using the tools available to them.

 

[SparkyChick]

The OP went on to reply with some details.

When the hood trips the breakers, it trips the two feeding upstairs and downstairs sockets, not the kitchen sockets.

He also went on to state that the kitchen was done about 4 years ago (I think it was 18 months after they moved in which was when the bulk of the rewiring was done) and that all the sparks who'd looked at it were reputable. The fault doesn't occur consistently which would explain why it's proving difficult to track down.

@Midwest suggested disconnecting the hood for a while to see if the fault occurs without it in use.

@Leesparkykent suggested it is a neutral-earth fault on one of the circuits that's tripping.

Beyond that, I can't remember much else

 

[Octopus]

Back to the OP ..... Has it ever worked properly?

Having tripping as you describe sounds VERY odd....

Clamp meter time

 

[SparkyChick]

He did state in one of his replies, that he believed the problem had started when the kitchen was done.

Long time to live with a fault that he believes causes a trip once every one or two weeks.

 

[hightower]

NE fault on hood I reckon. Mine does the same occasionally, CBA to fix/replace. Wife is still waiting for me to clean the windows which I said I'd do February 2016.

 

[D00DY_T00DY]

NE fault on hood I reckon. Mine does the same occasionally, CBA to fix/replace. Wife is still waiting for me to clean the windows which I said I'd do February 2016.

Just wait for that sideways rain

Or the window fairy.

 

[Tom Oxford]

If I write another reply, will the missing 2nd page of this thread reappear, I wonder...

He did state in one of his replies, that he believed the problem had started when the kitchen was done.

Long time to live with a fault that he believes causes a trip once every one or two weeks.

Can't believe I took so long to get around to posting on a forum only to choose a day when the server was being worked on and most of my effort was wasted, replies being lost!

I'll try and remember what I said yesterday. Sparkychick got a lot of it but I'll recap.

The extractor is on circuit 4 (kitchen sockets) but it trips circuits 5 & 6 (upstairs & downstairs sockets), usually both at once, though occasionally just one of them. It doesn't happen every time, which would be almost every day, but maybe once every week or two.

When we moved in nearly 6 years ago we had the kitchen ripped out and a lot of rewiring done. It was meant to be just adding/moving sockets and getting the kitchen electrics ready but the existing wiring was apparently dodgy and muddled and so quite a bit of rewiring was done. This was done by a reputable, qualified and experienced electrician. Some 18 months after that we had the kitchen installed, electrics being done by someone else (subcontracted by kitchen fitter). I think this was mostly connecting up.

Yes, it's a long time to live with a fault, but human beings are adaptable ;-) Also, when you've had 3 different qualified electricians test your system and none of them can find the cause, nor seem to think it's dangerous, what else can you do but live with it? Answer that belatedly came to me: ask around on the internet!

Someone seemed to suggest (though I may be taking his comment too literally!) that the issue with the hob sparking when other appliances start up was my imagination but it really does happen, and none of the famous 3 could answer that one either.

In one of my list replies I mooted showing your comments to one of the 3 electricians I've already seen (I know which one seems the most experienced) and seeing what he thought. It's been a couple of years since anyone had a look and I can't remember what they told me they'd looked for, so it may be some of your ideas have been tried already, who knows.

Any thoughts?

Oh, and thanks very much to all of you for contributing!

 

[Tom Oxford]

The posts that were made earlier in this thread have been lost due to the server move, I replied with this message.



I know it doesn't Pete and I can see the implication from my comment, sorry for that, but that's not what I meant. I know several great sparks who aren't members of the scams because they don't need to be, but for a householder it's a reasonably good place to start and I feel we should be encouraging householders to check people out using the tools available to them.

For what it's worth, as a layman, I felt Sparkychick was just making a suggestion of a good place to start in finding a good electrician and not casting any aspersions...

 

[SparkyChick]

The hob igniter... is it a big (relatively) push button or is it a touch control?