Oven tripping RCD regardless of setting

isitbroken

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Hello
I have a Lamona LAM3301 built in oven which was installed with the kitchen 6 years ago.
It is seldom used as I usually work away for long periods of time hence why I didn’t need a quality brand oven, just one that works on the odd occasion.

The RCD trips after the oven has been on 1 minute or so. It resets easily.
Initially I thought it was one of the elements.

I believe it has the grill/oven top element plus one in the bottom of the oven, but whether I select the grill alone, the fan assisted main oven, the main oven without the fan assisting, or just the bottom oven only it does exactly the same and trips after 1 minute.

Surely both elements wouldn’t go at exactly the same time so I am thinking is it a supply issue? With that said, if it was a supply issue would it not trip immediately-not after 1 minute of warming up?
 
Well no sparky ....but thinking about it logically....breakers trip out (as far as I know ) to either
something shorting out or overloading....as it's happening after a minute suggest it's probably due to an overload problem.

My built in oven works off a normal plug....which surprised me when it turned up (first one I've bought)

You could plug something else in to try or have the front off and check the socket just to make sure.

I'd probably un plug it take it out ..have the back plate off or whatever and have a good look round all the wiring just to check it's not something obvious ..like a corroded or burnt wire or something

I've replaced the element in my oven twice .....each time the oven has still come on ..with the fan working...just stayed cold

That's about all the help I can give you

Might be an idea to ask a sparky in general chat and or DIY section ?
 
Last edited:
What tends to happen is that the element fails and almost touches the safety shroud. The insulating material can become contaminated and this causes the partial earth fault and the breaker trips as things warm up. This is down to the way electronic like the oven timer are connected.

Once 1 element fails, any power applied to the oven can cause the trip. It could also be something common like a cooling fan that is causing the issue.

I would suggest that if you are competent with working with electrical equipment and have a meter, you could isolate the oven and check for the resistance between ground and the live terminal. Turn the various controls and see if the resistance drops. It should normally be a very high value, but should drop markedly when you find the fault.

Look for any severe burning or carbonising of the insulation material. Light colouring is normal, but it should not have gone crispy.

If you are not happy working with electricity, an oven is not the place to start. You get plenty of uncovered mains terminals once the cover is removed and some parts may be switched on the neutral, so terminals you would expect to be dead until switched off can actually be live.
 
What tends to happen is that the element fails and almost touches the safety shroud. The insulating material can become contaminated and this causes the partial earth fault and the breaker trips as things warm up. This is down to the way electronic like the oven timer are connected.

Once 1 element fails, any power applied to the oven can cause the trip. It could also be something common like a cooling fan that is causing the issue.

I would suggest that if you are competent with working with electrical equipment and have a meter, you could isolate the oven and check for the resistance between ground and the live terminal. Turn the various controls and see if the resistance drops. It should normally be a very high value, but should drop markedly when you find the fault.

Look for any severe burning or carbonising of the insulation material. Light colouring is normal, but it should not have gone crispy.

If you are not happy working with electricity, an oven is not the place to start. You get plenty of uncovered mains terminals once the cover is removed and some parts may be switched on the neutral, so terminals you would expect to be dead until switched off can actually be live.
An RCD trips due to earth leakage current, nothing to do with over current protection. An insulation resistance tester would have to operate at a voltage of 500 volts DC and be capable of maintaining a minimum test current for the duration of the test. Such sn instrument is available to buy, then you need to know how to use it and interpret the test results correctly. Would suggest you get someone competent in to test it.
 
An RCD trips due to earth leakage current, nothing to do with over current protection. An insulation resistance tester would have to operate at a voltage of 500 volts DC and be capable of maintaining a minimum test current for the duration of the test. Such sn instrument is available to buy, then you need to know how to use it and interpret the test results correctly. Would suggest you get someone competent in to test it.
Sorry, just trying to work out where in my post I suggested over current or using an old fashioned Megger to perform an insulation test...

If the RCD is taking a minute to trip, then something must be changing in that minute - and with an oven it will be something warming up most likely. Experience suggests that the most likely culprit is either a common component - such as a cooling fan that operates for both ovens, or one of the elements with a partial earth fault that gets worse as the oven warms up.

A basic electronic multimeter will register a change in the resistance between the earth and live connection if an earth fault exists in the oven. This is not a test of the insulation as such, but a quick and dirty way of trying to work out which element is to blame. Quite obviously the oven must be fully disconnected from the mains supply while checking this. From memory, a DC resistance of about 8K Ohms is enough to set off the trip, so if a reading of less than 10 K Ohms is seen, a fault has been identified.
 
The RCD is likely to be a 100mA type. On a 230 volt circuit the minimum resistance before the RCD trips is 230V/100mA = 2.3k ohms.
 
The RCD is likely to be a 100mA type. On a 230 volt circuit the minimum resistance before the RCD trips is 230V/100mA = 2.3k ohms.
Not in the UK in a domestic property. It will be 30mA.
 
Not in the UK in a domestic property. It will be 30mA.
In the UK if it's fitted into your consumer unit it is likely to be for property protection and will be the 100mA type. 30mA RCDs provide protection for property and personnel. If the RCD is fitted to protect the circuits in a split board, then it will be the 100mA type. In this case the larger size is fitted to prevent spurious tripping.
 
All I can say is I don't think I have ever seen a domestic board with a 100mA trip. Most are split boards with a pair of 30mA RCDs or RCBOs or a single 30mA RCD protecting all circuits except lighting.

Example of a current board here: MK Sentry 16-Module 10-Way Populated Split Load Main Switch Consumer Unit

And our slightly older property has a single RCD that protects all circuits except for the lighting, water heater and funnily enough the cooker!
 
Hello
I have a Lamona LAM3301 built in oven which was installed with the kitchen 6 years ago.
It is seldom used as I usually work away for long periods of time hence why I didn’t need a quality brand oven, just one that works on the odd occasion.

The RCD trips after the oven has been on 1 minute or so. It resets easily.
Initially I thought it was one of the elements.

I believe it has the grill/oven top element plus one in the bottom of the oven, but whether I select the grill alone, the fan assisted main oven, the main oven without the fan assisting, or just the bottom oven only it does exactly the same and trips after 1 minute.

Surely both elements wouldn’t go at exactly the same time so I am thinking is it a supply issue? With that said, if it was a supply issue would it not trip immediately-not after 1 minute of warming up?
It will be leakage that causes the RCD to trip. If you are familiar with electrical things, use an ohm meter to check the resistance. You will need to disconnect the power wire and measure between the earth wire and live and earth and neutral. The resistance should be very high Meg ohms. As @noiseboy72 said, turn on each control looking at the resistance. If it goes down, then you know you have a problem. Could be a failing element or failing insulation in a fan motor or a build up of crud around connections, causing earth leakage.
(a meggar is better but you are unlikely to have one of those I suspect)
 
It will definitely be one of the two elements but I doubt you will pick up an earth insulation fault with a multimeter unless you have pretty much a dead short, as has been said you need a meggar, alternatively disconnect one element at a time, insulate the wires and switch it on and see which element trips out.
 
All I can say is I don't think I have ever seen a domestic board with a 100mA trip. Most are split boards with a pair of 30mA RCDs or RCBOs or a single 30mA RCD protecting all circuits except lighting.

Example of a current board here: MK Sentry 16-Module 10-Way Populated Split Load Main Switch Consumer Unit

And our slightly older property has a single RCD that protects all circuits except for the lighting, water heater and funnily enough the cooker!
The last bit is a bit odd! Under the 17th Edition of the IIE Regulations. All special locations, such as a bathroom must have RCD protection + any circuits in a kitchen. Just so you know? Your 8k ohms reading has no bearing on the minimum permitted insulation resistance of you cooker circuit.
 
The last bit is a bit odd! Under the 17th Edition of the IIE Regulations. All special locations, such as a bathroom must have RCD protection + any circuits in a kitchen. Just so you know? Your 8k ohms reading has no bearing on the minimum permitted insulation resistance of you cooker circuit.
Yes, you are quite correct on both counts. Our house dates from 2001, so 16th edition applies. At some point I will get the DB updated, but at the moment I've simply fitted RCBOs for the cooker and immersion heater.

I am not talking about the insulation breakdown voltage, but when the element fails, it turns the insulation into a black, partially conductive gunge. This contains quite a lot of carbon and has a measurable DC resistance. Trust me, this works, as it was how I identified a similar fault on my oven. We had an issue that the RCBO would just trip randomly even with the oven switched off. It turned out that the main element had failed and was switched on the neutral by the timer, so the element was essentially "live" all the time. By isolating the cooker and putting a meter across the input on the highest range - 20MOhm in my case on my Fluke meter, a measurable difference was seen when the oven was switched on.
 
Ok thank you all for taking the time to write comprehensive replies.

Is it unlikely to be the cooker switch socket on the wall? Because if it is definitely not that I was thinking of just replacing the oven anyway. It cost very little indeed (either free with the kitchen or about £60 or something and it has been in there 6 years) and based on the reviews for Lamona ovens I have seen I could mess about with it only for something else to go on it next month. I am not electrically competent so I would have to get someone in to test the resistance etc so by the time I have factored that in then it is probably not cost effective for me to pursue it.

If it can’t be the wall socket if it is tripping after a minute I will get a new oven. I have already seen one I like :)
 
Very unlikely to be the wall switch. Sounds like just buy a new cooker and have it installed.
 
In the UK if it's fitted into your consumer unit it is likely to be for property protection and will be the 100mA type. 30mA RCDs provide protection for property and personnel. If the RCD is fitted to protect the circuits in a split board, then it will be the 100mA type. In this case the larger size is fitted to prevent spurious tripping.
A 100ma RCD is required where the installation supply is a TT earthing arrangement for most other it's 30ma.
Most towns are TNS/TNCS. TT tends to be rural areas.

The last bit is a bit odd! Under the 17th Edition of the IIE Regulations. All special locations, such as a bathroom must have RCD protection + any circuits in a kitchen. Just so you know? Your 8k ohms reading has no bearing on the minimum permitted insulation resistance of you cooker circuit.

We've been on the 18th regulations for well over a year with more additional protection regulations than the 17th contained.
The regulations are not retrospective so there is no need to add Rcd's to a installation that pre-dates the the regulations issued after its construction. ( All alterations must conform to the standard at the time of alteration)
 
A 100ma RCD is required where the installation supply is a TT earthing arrangement for most other it's 30ma.
Most towns are TNS/TNCS. TT tends to be rural areas.



We've been on the 18th regulations for well over a year with more additional protection regulations than the 17th contained.
The regulations are not retrospective so there is no need to add Rcd's to a installation that pre-dates the the regulations issued after its construction. ( All alterations must conform to the standard at the time of alteration)
TT is pretty rare in the UK these days due to the expense of maintaining the local earthing electrodes. We used to live in an isolated cottage with our supply derived from the overhead 10KV via a local transformer. Even that was TN-S with the electrode buried next to the pole. We had a standard fuse board with a 30mA trip - Oh and a little standby generator on a changeover switch for the lighting, freezer and central heating pump. Power outages happened on pretty much a weekly basis, as the supply was single ended and any fault would trip out miles of lines apparently!
 
Yes, fairly rare compared to the mainstream earhing, but I do still come accross them on occasion if working on a farm ect.
There's no requirement for the supplier to provide an earth with the supply! it's nice when they do but otherwise you have to make your own.
 
Ok great thank you.
I will buy a new AEG oven and start baking again like I used to :)
Thanks
I had this issue and it was the Oven heating element and cost £30 for me to fit. Turn mains off. Follow a guide to remove the backplate and inspect the element. It's likely to be a visible split.

Cheaper than a new Oven and AEG is a good brand.
 
It's one of the elements, I repair them that's why I've tried to give advice, i don't comment on things i know nothing about.
 
It's one of the elements, I repair them that's why I've tried to give advice, i don't comment on things i know nothing about.
Almost certainly it is an element.
I thought that had been decided already like your earlier post. I would change the element if it was mine but it also depends on the condition of the rest of the oven, Sometimes its better value to just buy new with a warranty.
 
Hello
I have a Lamona LAM3301 built in oven which was installed with the kitchen 6 years ago.
It is seldom used as I usually work away for long periods of time hence why I didn’t need a quality brand oven, just one that works on the odd occasion.

The RCD trips after the oven has been on 1 minute or so. It resets easily.
Initially I thought it was one of the elements.

I believe it has the grill/oven top element plus one in the bottom of the oven, but whether I select the grill alone, the fan assisted main oven, the main oven without the fan assisting, or just the bottom oven only it does exactly the same and trips after 1 minute.

Surely both elements wouldn’t go at exactly the same time so I am thinking is it a supply issue? With that said, if it was a supply issue would it not trip immediately-not after 1 minute of warming up?

I had exactly the same issue with a Siemens oven. It was the grill element insulation breaking down as it warmed up. So maybe you have issues with more than one heater element. Use the appliance with only one element connected at any one time to identify which have the fault. A RCD trips at a very low current differential (low enough and fast enough not to kill you if your body forms part of the current path).
 

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