Range Oven Tripping Circuit Breakers

[stephen atherton]

We just had a range oven fitted (gas on hob with two electric ovens - total power rated at 5.3Kw) so a 32Amp mcb is in the board on the dedicated cooker circuit which was there from previous cooker. When one oven is on everything works fine, but when both ovens are switched on together they trip the main 63Amp breaker in the consumer unit before the 32Amp mcb trips. It seems odd that both ovens work perfectly when on individually, but the minute you switch both on together they trip the main 63 Amp breaker in the consumer unit - this has been tested with everything else in the house switched off for all intents and purposes so there is nothing else bar the odd light and fridge still on - so no kettles, immersion heaters etc... Both ovens work great individually and nothing trips circuit breaker wise, but the minute they are both on together they trip out the entire consumer unit - the consumer unit is a 10 way split load and less than a year old so my thinking is a fault with the oven wiring and maybe a loose connection inside it as the oven is a second hand reconditioned one and not new from a store. Has anyone seen this fault before or maybe have an idea what the problem may be - bearing in mind both ovens do work individually? Thank you in advance

 

[telectrix]

i'll make an educated guess that that 63A device is an RCD. and there is sufficient earth leakage either in the ovens, or with the ovens combined with other devices, to trip it. does ithave a test button on it, like this:

 

[stephen atherton]

yes I think it does have a test button on it, it was an MK Sentry box from screwfix and I am sure there's a test button on it, just not home right now, but am sure it has a test button on it

 

[stephen atherton]

My partner says she is not bothered about only using one oven as she would only ever use two on Xmas day (wish I had known this before this big range was bought!!!) and says it's no big deal if she only had one oven on that day too, so she doesn't care - however, I would just like to see what the problem may be and see if I can resolve it.

 

[telectrix]

then it tripping through earth leakage. could be damp in the oven elements, or a combination of small faults adding up to breach the 30mA threshold of the RCD. afraid you will need a competent electrician with the relevant test gear to sort this one. but first, i'd switch each oven element on, one at a time and allow each to run hot for a while, then switch 1stone off and do same with 2nd, etc. then try them all together.

bear in mind that a RCD does not trip on overload or short circuit, so those 2 can be dismissed as causes.

 

[Octopus]

So the 2nd unit is tripping the RCD. How old is it? Has it just been professionally cleaned?

 

[stephen atherton]

Both ovens work great individually, but when both are on they trip the RCD - however the fact this is reconditioned with new elements in it and it has stood in a damp house (being done up) for nearly eight months. So I will switch each oven on individually for an hour and see if it helps (thanks telectrixs). After that I will take a look at the earth connections in the board and at cooker switch and see if something may be a little loose - might be in the cooker as the cable looks brand new so someone will have done that when reconditioning it...

 

[Octopus]

A loose earth at the cu wouldn't trip the RCD.....

 

[Pete999]

We just had a range oven fitted (gas on hob with two electric ovens - total power rated at 5.3Kw) so a 32Amp mcb is in the board on the dedicated cooker circuit which was there from previous cooker. When one oven is on everything works fine, but when both ovens are switched on together they trip the main 63Amp breaker in the consumer unit before the 32Amp mcb trips. It seems odd that both ovens work perfectly when on individually, but the minute you switch both on together they trip the main 63 Amp breaker in the consumer unit - this has been tested with everything else in the house switched off for all intents and purposes so there is nothing else bar the odd light and fridge still on - so no kettles, immersion heaters etc... Both ovens work great individually and nothing trips circuit breaker wise, but the minute they are both on together they trip out the entire consumer unit - the consumer unit is a 10 way split load and less than a year old so my thinking is a fault with the oven wiring and maybe a loose connection inside it as the oven is a second hand reconditioned one and not new from a store. Has anyone seen this fault before or maybe have an idea what the problem may be - bearing in mind both ovens do work individually? Thank you in advance

The "63 Amp breaker" you talk of that would an RCD wouldn't it? which I think indicate an earth fault on one of the ovens

 

[telectrix]

better late than never, pete. posts #2 and #5.

 

[Pete999]

better late than never, pete. posts #2 and #5.

My excuse, I just got back fro Tesco and I'm frazzled, still I should have read the entire post

 

[Des 56]

You have tried using the ovens with everything else switched off
Have you tried disconnecting as many of these items as possible,unplugging rather than switching off
It will disconnect the neutrals and remove a low neutral-earth on another circuit that may be playing a part

 

[Midwest]

My excuse, I just got back fro Tesco and I'm frazzled, still I should have read the entire post

Don't be overly embarrassed Pete, seen loads of other members doing this recently, in other threads. Too keen to bump their gums

 

[Octopus]

I would be using my earth clamp meter to check for the site earth leakage...

 

[UNG]

Think I would be ramp testing the RCD.
Had one the other day on an EICR that was tripping at 19mA

 

[Toneyz]

Think I would be ramp testing the RCD.
Had one the other day on an EICR that was tripping at 19mA

This is the problem sometimes I=they do not trip at 30mA it is below that and the commutative sum of other leakage currents either/or other circuits other oven.

 

[Midwest]

I was told by one manufacturer that 21mA was an acceptable tripping value. Most I've ramped seem to have been around that value.