Any electricians around here, our cooker keeps tripping the RCD even with 2 replacments.

Iamzod · 14 Dec 2025 at 13:57

We bought an induction topped freestanding cooker, it initially worked for about 25 minutes & then started tripping the RCD whether any of the ovens or hob was on or not, it's probably easier to bullet point the sequence of events -

The manufacturer initially sent out someone who tested it & said that it had an internal earth leak requiring parts.
Another guy came a week later & replaced a control board, however he was still reading a leak in the cooker (1.6 on a megohmmeter so arranged a replacement cooker)
Replacement cooker came & tripped the RCD immediately, upon resetting it it then worked but tripped the RCD after precisely 3 minutes every time, apart from once when we managed 4 minutes & 16 seconds.
Engineer came out, tested cooker & the wiring to it, wiring he said was fine but Megohmmeter reading 1.8 he said was no good, replacement arranged.
Replacement cooker arrives this morning, get it connected & I successfully boil a pan on it. I then turn the top oven on to burn the oil off the elements from it being new & it lasts 19 minuts and pop, RCD tripped. Now we are back to it tripping the RCD exactly every 3 minutes.

What could be going on?

Any ideas?

Molep · 14 Dec 2025 at 14:21

Cable back to RCD adequate rating?

Iamzod · 14 Dec 2025 at 14:28

Molep said:
Cable back to RCD adequate rating?

Yeah, it's new. I've managed since posting to get the oven to run if it's on & the other circuits are off.

I'm now powering up the house bit by bit 1 at a time every 5 mins as i'm wondering if something kicks in 3 minutes after a trip that's tipping the RCD over the

Could it be cumulative leakage but why were the last 2 ovens deemed faulty by engineers? puzzling.

Nemiyen · 14 Dec 2025 at 14:49

If it's the same thing tripping the electrics and it wasn't tripping before, maybe you just need a refund on the cooker and buy a better brand or model?

I'm guessing they did a PAT test of some description so if it's failing that then it sounds like a bad design or build?

Iamzod · 14 Dec 2025 at 14:54

Nemiyen said:
If it's the same thing tripping the electrics and it wasn't tripping before, maybe you just need a refund on the cooker and buy a better brand or model?

I'm guessing they did a PAT test of some description so if it's failing that then it sounds like a bad design or build?

Maybe, but i've now had it at full tilt for 52 mins & it hasn't tripped so i'm wondering if they are getting damp in storage & the heating elements are absorbing moisture.

All but 1 circuit live now & still no trip.

Dangerous Dave · 14 Dec 2025 at 15:00

It is accumulative my mum had this with a shower, there was a multiblock with a failing led that was introducing more leakage which the shower then took over the limit and tripped the RCD.

Iamzod · 14 Dec 2025 at 15:27

Dangerous Dave said:
It is accumulative my mum had this with a shower, there was a multiblock with a failing led that was introducing more leakage which the shower then took over the limit and tripped the RCD.

Looking that way. I can get every circuit on but as soon as the heatpump kicks in with the cooker connected. Pop.

That's what was happening at 3 minutes, i'm guessing the house was warm enough for the oven to work but it's kicked in & tripped it after 20 and then at evert reset when the heatpump repowers & realises the house has chilled off it's kicking in at 3 mins & tipping it over.

If i disconnect the heatpump or the cooker all is fine. Or i can have both on if I disconnect the kitchen & living room plug sockets where loads of appliances are connected.

Looks like the CU may need looking at.

jpaul · 14 Dec 2025 at 16:08

the heat-pump is an example you are giving of what dave said , or a co-dependence you already discovered (after engineer visit, so he didn't know) for tripping to occur ?

There was an accumulative thread on here where someone found a socket was unexpectedly on wrong circuit and its appliance contributing to a trip.

Dangerous Dave · 14 Dec 2025 at 16:50

One option you have is a split CU so you can put them on different RCDs. Helped in my mum’s case as she only lost half the house when it was tripping.

If it’s the heat pump circuit worth checking for any moisture in the components outside.

koolpc · 14 Dec 2025 at 16:53

When my cooker kept tripping i bought it glasses so that it could see where it was going!!

Nemiyen · 14 Dec 2025 at 20:56

If you do end up going with a new CU then you may as well go for a full RCBO one so each ring is on its own RCD equivalent.

I didn't pay much attention until now but our entire house sockets are on one ring or circuit! For some reason, even the kitchen sockets.

We had an MCB in the CU that wasn't even wired up, I just presumed it was the kitchen or downstairs sockets but never needed to mess around.

Thankfully, everything that's plugged in and working must be in spec as we don't have any trips but it does bug me the house was wired this way.

Nigel Kingdon · 15 Dec 2025 at 09:44

I'm not a sparky, but I thought that electric oven and induction hob have to have separate spurs? Is the induction hob a large one as they require a 45amp spur IIRC?

K.C. Leblanc · 15 Dec 2025 at 11:33

Nigel Kingdon said:
I'm not a sparky, but I thought that electric oven and induction hob have to have separate spurs? Is the induction hob a large one as they require a 45amp spur IIRC?

It depends how much power they require,

But in many consumer units the RCD is shared between multiple circuits. This isn't ideal, since in most domestic situations a 30 miliamp rcd will be used irrespective of how many circuits it's protectings. 30ma is chosen because it's a level when an electric shock is very unlikely to be fatal.

Sinbad2000 · 15 Dec 2025 at 11:38

How old is the RCD? they do go bad eventually and get too sensitive.

Iamzod · 15 Dec 2025 at 12:31

Sinbad2000 said:
How old is the RCD? they do go bad eventually and get too sensitive.

It was replaced about 5 years back as it broke.

Nigel Kingdon said:
I'm not a sparky, but I thought that electric oven and induction hob have to have separate spurs? Is the induction hob a large one as they require a 45amp spur IIRC?

It's a freestanding unit. The hob & ovens are a single appliance.

Iamzod · 15 Dec 2025 at 12:33

K.C. Leblanc said:
It depends how much power they require,

But in many consumer units the RCD is shared between multiple circuits. This isn't ideal, since in most domestic situations a 30 miliamp rcd will be used irrespective of how many circuits it's protectings. 30ma is chosen because it's a level when an electric shock is very unlikely to be fatal.

This is our setup, the entire house is on a single 30ma RCD & we have electrical everything, batteries, cooker, inverter etc.

jpaul · 15 Dec 2025 at 13:27

Another issue would be if you have the right type of rcd for heat pump, and batteries/invertor - type B ? (like I found I needed for commando ev charger)
otherwise they maybe the real problems , themselve generating localised voltage deviation that caused hob's power supply to react adversely.

matgsi · 15 Dec 2025 at 14:24

I'm not an electrician, but as already mentioned I'd try changing the individual RCD. As has been said, they can become more sensitive with time.

Nemiyen · 15 Dec 2025 at 17:05

Nigel Kingdon said:
I'm not a sparky, but I thought that electric oven and induction hob have to have separate spurs? Is the induction hob a large one as they require a 45amp spur IIRC?

Luckily for us, the oven is electric but the hob is gas.

I can't imagine the amount of times our oven, ninja, microwave and kettle might be on at the same time but adding that all up, it's still probably less than an EV charger and only when pulling the full amounts.

I'll just need to be careful not to put both my delonghi dragon radiators on at the same time!

K.C. Leblanc · 16 Dec 2025 at 09:54

matgsi said:
I'm not an electrician, but as already mentioned I'd try changing the individual RCD. As has been said, they can become more sensitive with time.

That isn't a DIY job, depending on how the OP's installation is setup it may not be possible to isolate the main CU without removing the suppliers fuse.

An electrician would have the correct test equipment to test the RCD and also check the amount of earth leakage with equipment running.

While it may be the RCD is faulty it's more likely it's just cumulative earth leakage. Unfortunately earth leakage is a bigger issue with modern electronics and single RCD installations don't work well. This is why new installations aren't done this way.