Why is oven tripping rcd?

[Calebp43]

Every time oven gets to temperature it trips the RCD. Thought the oven must be knackered so got a new one. That does the exact same thing. Any ideas? I should add that this is a brand new house. Just moved in yesterday

 

[Electro-tech]

I would get an electrician to test the supply cable to the oven, being a new house does not mean much as it could be a nicked or pinched cable at an accessory & underload trips. Get an electrician to test the complete circuit including the Earth integrity at the oven, and look for excessive earth leakage as well.

 

[Dustydazzler]

My oven is very temperamental , it trips the rcd sometimes when I turn it on and sometimes when I turn the main dial off

I have done all the tests on the cable between the consumer unit and the cooker connection plate and it all test fine

 

[DPG]

My oven is very temperamental , it trips the rcd sometimes when I turn it on and sometimes when I turn the main dial off

I have done all the tests on the cable between the consumer unit and the cooker connection plate and it all test fine

Get Delroy round He's got an MFT now I believe

 

[pc1966]

If it happens every time and you have changed the oven then it is very unlikely to be the oven, more likely a wiring fault.

Simple faults typically would trip instantly so the suggestion above that it is something getting hot and triggering it makes sense.

My own oven (30 year old NEF thing) trips the RCBO around twice a year, typically though when I turn it off so probably just neutral breaking first or similar causing a little current spike. Usual static checks (IR and leakage current) did not show anything to worry about, just a mild annoyance due to the fscking stupid location of my CU. But one I could not realistically change when replacing it a couple of years back.

 

[Dustydazzler]

Get Delroy round He's got an MFT now I believe

Indeed He has a lovely shiny Megger

But I don't see how is Megger would show anything different than my old Fluke does

I have IR the cable , done an EFLI test and RCD test and all the tests are fine

That said I would love an excuse to meet Del and the banter would be worth the £150 call out fee , even if he didn't manage to fix me oven

 

[pc1966]

Just thinking about my case - I wonder if the OP's oven has been wired reverse polarity to the thermostat is breaking the neutral?

A sparky ought to check that. Has your cooker got a 13A socket outlet? If so then a socket tester in it might be a very good thing to begin with.

 

[LastManOnline]

Just thinking about my case - I wonder if the OP's oven has been wired reverse polarity to the thermostat is breaking the neutral?

Definately worth checking.The common factor is that both ovans tripped rcd when desired temperature is reached.It would seem the temperature itself is not the trigger but the circuit that is been switched as a result of the temperature.The switching mechanism may well be the key to the probem and checking polarity would be a good place to start

 

[brianmoooore]

How many times has the new oven tripped the RCD? The type of element typically used for ovens can absorb moisture if left unused from new for a while in less than perfect conditions, and from the time when I used to repair the odd domestic appliance, I know that it's not at all unusual for a new element of this construction (oven, grill, or old type spiral hob) to electrically leak enough to trip a RCD as it heats up. Typically, the leakage resistance will be satisfactory when the element is cold, and decrease as it heats up.
After a while, the moisture is driven out, and the element stays within leakage limits.

 

[nicebutdim]

Brand new house the OP moved into yesterday!

Was the oven new? If not, and it hadn't previously caused issues (assuming it was powered by an RCD protected circuit), had it been in storage for a period of time? Was the replacement oven new?

It seems odd to buy a new oven to replace one that is a day old.

 

[Calebp43]

Just so everyone knows. It was the oven that was faulty. New oven fixed the issue

 

[Lucien Nunes]

As per @brianmoooore and others it is quite common for new and little-used heating elements to develop high leakage due to moisture ingress. The moisture bridges the mineral insulation causing electrical leakage, which tends to get worse as the element first heats up because the moisture concentrates towards the cooler ends.

However, the specific effect of tripping when the oven reaches the set temperature is possible indicator of reversed polarity. When a single-pole thermostat opens in the neutral instead of the line, the entire element swings up to line potential, which could suddenly double the earth leakage caused by moisture and cause the trip. A new oven with a dry element that has low leakage won't cause this effect, so if the polarity is reversed it might be that the new oven appears to have solved the problem when in fact it has merely hidden it.

I would like to think that whoever changed the oven checked the polarity, do you know if they did?