Intermittent Trip Help

[Iainpatch]

Hi

I know there are loads of threads on tripping but I couldnt find one that seems to fit my problem. Also im not an electrician so apologies in advance.

I have an oven that was fitted brand new as part of a new kitchen which is causing an intermittent (once a day) trip on the main house RCD (not the individual oven breaker). I "know" it is the oven causing the problem because if I switch the oven off at the control unit then there is no trip. (that only took a few weeks to work out!). I think this also means that it is a live - earth problem?

Ive had a look at the control unit and there are no obvious touching or broken wires and there is no water. Im really hoping its not the oven itself as its brand new.

Struggling on what should I try next?

Should I wire an appliance that I know does not cause a trip into the oven control unit feed and see if the trip continues? I guess that would tell me if its the oven or the wiring?

Any suggestions / comments gratefully received.

PS the guy who fitted doesnt want to know. So getting him back isnt likely.

 

[Iainpatch]

Sorry thought worth adding...... Its doesnt seem to be a load issue. I can run the oven full power with lots of the appliances on and I get no trips.

But if I leave the oven powered on (not running) it will randomly trip about once every day.

 

[JohnD]

it may be an accumulation of earth leakage.

most often these faults are found in watery appliances, such as kettles, immersion heaters, fishtanks, washing machines, dishwashers, immersion heaters, tea urns, espresso makers, and outdoor lamps in the rain. Then elements such as oven heaters, but more often when they are old. Computers have a small leakage.

It might be that your oven (or do you mean cooker?) has a leakage of 15mA, your computer of 10mA and your fridge defroster of 5mA. If they all happened to be on at the same time, it would be enough, added together, to cause a trip.

You can try unplugging your other appliances to see if you can detect a pattern. Or you could ask an electrician with a PAT instrument to test your plug-in appliances.

Look for any signs of damaged cable or flex, for example in the cooker is crushing its cable. Or signs of water, for example dripping from a bathroom or kitchen leak or spillage.

Intermittent earth faults can be time consuming to trace.

Show us a photo of the breakers in your consumer unit, and a general photo showing the cables around your meter and CU to give an impression of the installation.

 

[JohnW2]

Should I wire an appliance that I know does not cause a trip into the oven control unit feed and see if the trip continues? I guess that would tell me if its the oven or the wiring?

You could, but I'm not sure it would be worth it. If the trips occur when the over control unit is switched on, but not when it's switched off, that pronbably points a finger at least partially at the oven, although its' possible that the high load of the oven is 'showing up' some other problem in your installation (or with other appliances). Do the trips occur regardless of what other things you do, or don't have switched on?. The problem with doing what you suggested is that you would really need to connect some other appliance which used as much power as the oven (to ascertain whether it was just the high current revealing some other problem), and that might be hard to find.

Do the trips occur when the control unit is switched on even if the oven is not switched on?

It's theoretically possible that there are faults both in the oven and the wiring, but that would be exceptionally 'unlucky'!

Do I take it that the oven is not still under warranty? Has this been happening ever since you had the oven fitted?

Kind Regards, John

 

[Iainpatch]

Hi guys, thanks for the responses.

I may not have explained this well, apologies. The trips happen when the oven/cooker is powered on but not running. It's not a load thing. I can run all my house appliances plus cooker on full power and I get no trips.

But if I leave the cooker with power on (ie the lcd lights are on but it's not actually running) it will randomly trip the whole house RCD, about once a day.

I know it's the cooker doing it because if I switch the power to the cooker off completely (at the control box) the trips don't happen. (I've taken several weeks of trying things to work that out).

 

[JohnW2]

I may not have explained this well, apologies. The trips happen when the oven/cooker is powered on but not running. It's not a load thing. I can run all my house appliances plus cooker on full power and I get no trips. But if I leave the cooker with power on (ie the lcd lights are on but it's not actually running) it will randomly trip the whole house RCD, about once a day. I know it's the cooker doing it because if I switch the power to the cooker off completely (at the control box) the trips don't happen. (I've taken several weeks of trying things to work that out).

Thanks for clarifying - that's essentially what I thought you meant.

As you realised, that puts paid to any thoughts of the high load revealing N-E faults in other circuits/appliances. There clearly is a fault to earth within the cooker which, alone or in combination with leaks/faults in other appliances.wiring, is causing the trips. As far as I can see, the only way you could go some way to finding out whether the problem is essentially down to the oven alone is to switch off/isolate everything else in the house you possibly can that runs on circuits protected by the same RCD and see if the oven still causes trips.

Kind Regards, John