RCD (sometimes) trips on switching OFF an ELO

[telectrix]

just to get back to a sensible theme...... it is sounding to me like the gremlins have got into the |RCD. for what it costs, try replacing the RCD.

 

[charlhu]

danke schon.

Im Deutschland habst sie gut essen? Ich glaube nicht!

 

[charlhu]

just to get back to a sensible theme...... it is sounding to me like the gremlins have got into the |RCD. for what it costs, try replacing the RCD.

For the electrics of my kitchen renovation project I will now replace the RCD as a matter of course - it is 4-5 years old anyway. But that cannot be the problem. If I just leave the oven alone my whole house operates fine with never a trip as it has done for the past 4 years. The problem only manifested itself when I recently replaced the old cooker (no problem then) with the ELO/Ceramic Hob combo in anticipation of my eventual set-up. The old cooker was a bit of crap. There is no doubt that the problem is somwhere in the oven installation.

 

[charlhu]

That's true, but even if the isolator is used to disconnect L & N going to the cooker, why would arcing there trip an RCD that those L & N are not going through? IE - when the RCD trips it appears from the posts above that the cooker is still working, so I assume that the cooker circuit is not (or is not only) connected to the RCD in question.

Is is possible to have some photos of the Consumer Unit both with the front on (to see the labelling) and off (having first switched off, of course)?

Many thanks for the helpful suggestion of photos - will post some tomorrow.

 

[nickblake]

I think you may have hit it!
When I originally bought and installed this oven in France it had a cable with a continental plug and there was socket in the kitchen for it on a separate circuit from the hob. I put it down to differing electrical systems (e.g. they use fused circuits, individual neutrals back to the board, etc) so without further thought I just put it on to the cooker circuit as I described. Seems that could be the root of the problem. Also your theory of "cumulative small leakages" reaching the trip threshold makes a lot of sense and I will try to check it out by disconnecting everything in sight though ithat may not be conclusive as it doesn't trip "on request".
Either way it seems that it would be best to have a separate circuit installed. I don't entirely understand your wiring proposal - If it is cabled back to a 32A MCB on the board it somehow has leakage protection separately from the existing RCD? If I go that route I'll get an electrician in to do it but would like it to be a case of him implementing a viable solution not confronting a problem.

what i did point out that there could be over load 1.5 cable is rated around 16.5 amps , it would have been protected by a 32amp mcb so if a fault developed within the cooker it may not nesseseraly trip the MCB ,cumulitaive leakage could be a possability ,but i have been thinking about this , what could be a possability is that the supply cable to the oven has been wired incorrectly live and neutral reversed then it will definatly trip the RCD when switched off as its disconnecting the neutral not the live causing an imbalance ,clair could well have been right with the neutral assumption

 

[pushrod]

For the electrics of my kitchen renovation project I will now replace the RCD as a matter of course - it is 4-5 years old anyway. But that cannot be the problem. If I just leave the oven alone my whole house operates fine with never a trip as it has done for the past 4 years. The problem only manifested itself when I recently replaced the old cooker (no problem then) with the ELO/Ceramic Hob combo in anticipation of my eventual set-up. The old cooker was a bit of crap. There is no doubt that the problem is somwhere in the oven installation.

Have you actually re-checked the terminations you did for tightness, etc?


When the oven is switched off at the appliances is there still a clock working on it?


A pic of the fuseboard would certainly help - are you saying that the cooker circuit is on the non rcd side of the board and takes out the rcd which is controlling just 2 power circuits?

Some of your understanding and logic does not actually hold up and to be honest you should not be doing anything to your consumer unit unless you are properly competent and have test equipment, regardless of part P regulations. You have had the benefit of many experienced sparks here and it has been said numerous times that it really should be tested properly.

 

[charlhu]

Have you actually re-checked the terminations you did for tightness, etc?

SEVERAL TIMES


When the oven is switched off at the appliances is there still a clock working on it?

YES


A pic of the fuseboard would certainly help - are you saying that the cooker circuit is on the non rcd side of the board and takes out the rcd which is controlling just 2 power circuits?
CORRECT. On the RCD side: Two power circuits. On the non-RCD side: cooker circuit/lighting circuit/security alarm circuit. And Yes, it does take out the RCD cutting out the power circuits but not the cooker/lighting/security circuits.
Some of your understanding and logic does not actually hold up and to be honest you should not be doing anything to your consumer unit unless you are properly competent and have test equipment, regardless of part P regulations. You have had the benefit of many experienced sparks here and it has been said numerous times that it really should be tested properly.

I am NOT doing anything to the Consumer Unit. As I thought I had made clear - if work on the CU proves necessary then I shall call in a registered electrician for that. What I am trying to do is avoid an unneccesary call-in and nothing to date suggests a problem at the board or the distribution wiring. The problem clearly starts at the cooker switch.To cable from there to an oven does not need an electrician - it is just everyday DIY commonsense. The cooker switch is demonstrably OK when used solely for the ceramic hob so that only leaves the cable from the cooker switch to the oven and the oven itself. Since everything has been trouble-free for 4 years and remains so except when the newly installed oven comes into the picture, with due respect, testing components that can be demonstrated to be operating satisfactorily is a red herring.

 

[telectrix]

Im Deutschland habst sie gut essen? Ich glaube nicht!

sorry, my grasp of german is limited to danke, bitte, achtung spitfeur

 

[topquark]

Im Deutschland habst sie gut essen? Ich glaube nicht!

Jah, das shmekt immer gudt!

 

[telectrix]

long shot i know but possibility of a neutral link/short/leakage between the cooker circuit ann 1 of the circuits on the RCD?????

 

[pushrod]

For the electrics of my kitchen renovation project I will now replace the RCD as a matter of course - it is 4-5 years old anyway. But that cannot be the problem..

I am NOT doing anything to the Consumer Unit. As I thought I had made clear -

All i did was read your earlier post and the rcd cannot be the problem

testing components that can be demonstrated to be operating satisfactorily is a red herring.

So you know that your rcd is tripping at the correct current You know that all your insulation resistances and continuities are all ok and within acceptable limits You know there are no N/E faults anywhere. You know if there are other earth leakage currents or even if your cooker has one

Well you obviously don't need any advice from me!
I wonder why i have £1000+ of testing kit

 

[nickblake]

The more i think about it the more i feel that the polarity from the cooker point to the oven in the wrong way round , thus switching the neutral this will cause random tripping of the RCD

 

[telectrix]

yeah , nick, but i think it was stated that the tripping iccured when the cooker isolator was switched off, and that's double pole.

 

[MarkieSparkie]

I believe the problem here is likely to be at the distribution unit. Most likely the cooker circuit neutral has been incorrectly terminated in the RCD side neutral bar, allowing switching transients to impress, common mode, an out of balance current which adds to the quiescent leakage of the RCD controlled circuits and thus tripping the RCD. The slightly random nature of the tripping action is cause by the point on the sine-wave cycle at which the switching action takes place, i.e. near either peak cause tripping but near the cross-over does not.

 

[charlhu]

I believe the problem here is likely to be at the distribution unit. Most likely the cooker circuit neutral has been incorrectly terminated in the RCD side neutral bar, allowing switching transients to impress, common mode, an out of balance current which adds to the quiescent leakage of the RCD controlled circuits and thus tripping the RCD. The slightly random nature of the tripping action is cause by the point on the sine-wave cycle at which the switching action takes place, i.e. near either peak cause tripping but near the cross-over does not.

Thank you for the thoughtful post and I followed up your idea. Unfortunately, if you check out my latest post today and attached photos I think you might be satisfied that the cooker circuit neutral is correctly terminated on the non-rcd side of the neutral busbar.

 

[sparkinlee]

...if you check out my latest post today and attached photos...

I must be missing something - I can't see a post with photos attached. Can you point me in the right direction?

 

[charlhu]

Thank you for the thoughtful post and I followed up your idea. Unfortunately, if you check out my latest post today and attached photos I think you might be satisfied that the cooker circuit neutral is correctly terminated on the non-rcd side of the neutral busbar.

NB: The post is a new thread.

 

[charlhu]

I must be missing something - I can't see a post with photos attached. Can you point me in the right direction?

To make attachments I had to start a new thread which i completed just a couple of minutes ago

 

[charlhu]

yeah , nick, but i think it was stated that the tripping iccured when the cooker isolator was switched off, and that's double pole.

I have started a new thread with attachments updating the facts.

 

[charlhu]

The more i think about it the more i feel that the polarity from the cooker point to the oven in the wrong way round , thus switching the neutral this will cause random tripping of the RCD

I have started a new thread with attachments updating the facts.

 

[charlhu]

Jah, das shmekt immer gudt!

Touché.
I have started a new thread with attachments updating the facts.