RCD (sometimes) trips on switching OFF an ELO

[pushrod]

A cooker switch is really a double pole isolator. Isolators as such are not really intended for switching in the way that a light switch is (under any load) - speed of separation of contacts, distances and hardening of contact points. It is possible that you are getting arcing at this point that causes the rcd to trip.

 

[topquark]

As pushrod has said (we're assuming you are talking about the cooker isolator when you way the main switch) the isolator is not the way to turn the cooker on/off.

 

[sparkinlee]

As pushrod has said (we're assuming you are talking about the cooker isolator when you way the main switch) the isolator is not the way to turn the cooker on/off.

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)?

 

[telectrix]

could it be the surrender monkeys getting revenge for waterloo?

 

[charlhu]

A cooker switch is really a double pole isolator. Isolators as such are not really intended for switching in the way that a light switch is (under any load) - speed of separation of contacts, distances and hardening of contact points. It is possible that you are getting arcing at this point that causes the rcd to trip.

Yes, of course - I don't normally use it for anything other than its intended purpose of isolating the cooker/oven/whatever if I am going to work on it. The point is I have been trying all conceivable operations as a diagnostic. With the oven switched off it is operating under a no-load condition so should not arc. Furthermore, as stated, it does not cause a trip when only the ceramic hob is wired in - arcing would ocur irrespective of what was connected downstream.
The question remains unanswered so far - why does it trip the RCD when the cooker circuit is not on the RCD? In the trip condition the oven circuit is fine - it is the two power circuits that the RCD controls which go down.
I have checked the relevant IEE Regulation 5.9.3 and my installation (installed by a registered electician 4 years ago when I had all the wiring updated) conforms exactly. It is a bungalow so the "ground floor" power circuits are RCD protected but nothing else. There is no requirement for cooker circuits to be on RCD and mine is not. So any line/neutral imbalance is not measured. Mystery?

 

[charlhu]

could it be the surrender monkeys getting revenge for waterloo?

You could be on the right track but more likely to prevent first-rate French cooking equipment being used to prepare British "cuisine". This is the only country I know of where appiance manufacturers offer a "double microwave" option.

 

[telectrix]

You could be on the right track but more likely to prevent first-rate French cooking equipment being used to prepare British "cuisine". This is the only country I know of where appiance manufacturers offer a "double microwave" option.

french cuisine??? smelly mouldy cheese, frog's legs, cold soup, shergar, piat d'or ( translates as golden p*ss ), croissants, whatever they are. i'll stick to my fry-ups and rare steak & chips.

 

[truckster]

french cuisine??? smelly mouldy cheese, frog's legs, cold soup, shergar, piat d'or ( translates as golden p*ss ), croissants, whatever they are. i'll stick to my fry-ups and rare steak & chips.

I am upstanding giving you a full salute, you british bulldog you

 

[telectrix]

danke schon.

 

[charlhu]

As pushrod has said (we're assuming you are talking about the cooker isolator when you way the main switch) the isolator is not the way to turn the cooker on/off.

i have only referred to the "Cooker Switch" (OK "cooker isolator" if you prefer - but all the elec suppliers list them as "switches") never used "main switch" which I would take as the Mains Isolator on the board.

 

[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?????