Steam from gas hob trips oven / consumer unit

[Skylark NW]

We have a Bosch built-in oven, HBN531.0B, located below a Bosch 4-ring gas hob, installed around 8 years ago.

A few months ago, steam/condensation/water from cooking seemed to cause the consumer unit to trip. With it turned back on, as soon as I tried to set the clock on the oven, it tripped again. Waited overnight, presumably for things to dry-out, turned on the oven and all was fine.

It's done this a few times since, including yesterday evening. Two hours after cooking, the consumer unit tripped.

Does this sound symptomatic of a known issue? Is there a DIY fix or can anyone recommend an electrician convenient to Altrincham/south Manchester?

Many thanks.

 

[ericmark]

One reason I don't cook on gas, there are a few likely problems.
1) Gas appliances need a hood vented to outside to remove exhaust gases where electric can use a simple carbon filter and the exhaust gases include moisture generated by burning gas, not just boiling food.
2) The elements used in an electric oven are mineral insulated and are hydrophilic that is it attracts water, there is a seal at end, but once seal damaged only cure is new element however in this case they don't normally dry out themselves they need changing.
3) Which seems likely, not related to the oven, you may have a neutral - earth problem. When there is no load, neutral and earth are at same voltage, so any low resistance link like bit of damp toast in toaster, will not cause it to trip, but once the load increases for example turning on the oven, the voltage between earth and neutral increases, so current flows causing the RCD to trip.

So step one unplug any items which are class I i.e. uses an earth, that are not in use, class II (double insulated) will not matter, but things like toaster and microwave can cause the RCD to trip when oven used if left plugged in.

 

[Skylark NW]

Thanks for the response, much appreciated.

There is nothing else plugged in when it trips. Each time it has happened, it has behaved the same. Turn back on at the consumer unit. The clock on the electric oven will flash. Immediately after starting the set clock process, it will trip again. Leave the oven off at its main kitchen wall switch overnight, turn on again the following morning, set the clock and all is fine.

Any further comments?

 

[ericmark]

I have all RCBO's so in my case the trip only feeds cooker, but I had assumed it was a RCD tripping, and most people one RCD feeds many circuits. If the MCB is tripping then more serious.

So what is tripping

a RCBO has a test button as does a RCD the MCB has no test button, and isolator normally red lever.

 

[Skylark NW]

Thanks for the reply.

Picture of the consumer unit attached. The first black switch on the right, immediately to the left of the two red main switches, trips.

 

[flameport]

Most likely is a failing element in the oven. As it trips all the time, it should be a simple task to have en electrician test the element(s) to locate the defective one.

 

[opps]

Have you looked in the oven at the top plate (read: lid)?

My mum's £1300 microwave combi oven needs to be replaced because of rust.



In her case, and not yours, the installation instructions do say that an air vent in the pinth should be fitted to allow the air to flow up and out of the top of the oven. Her's is about 8 years old as well.

I am a tad confused though. When you say it trips after two hours, do you mean that the oven will trip when turned on and empty? At a guess the oven has three heating elements, the one in the base, the grill on at the top and the circular fan at the back. You could always remove the wires to one of each and see what happens?

Other than that, checkout one of the dedicated "white goods" forums. This site is great but there are other specialised forums.

 

[Alec_t]

"Steam from gas hob trips oven"
I'm curious as to how steam from cooking on the hob can affect the oven, which is below the hob? Isn't your kitchen vented? Is the oven supply switch/fused spur in the path of the steam?

 

[flameport]

steam from cooking on the hob

Steam/moisture from the oven. Hob is unrelated.

 

[Alec_t]

Hob is unrelated.

That's not what the thread title states.

 

[Skylark NW]

Most likely is a failing element in the oven. As it trips all the time, it should be a simple task to have en electrician test the element(s) to locate the defective one.

It's only ever tripped when the oven is off/cold. Water from gas hob cooking somehow causes the consumer unit to trip. The only electrical load appears to be the clock.

 

[Skylark NW]

Have you looked in the oven at the top plate (read: lid)?

My mum's £1300 microwave combi oven needs to be replaced because of rust.

View attachment 247479

In her case, and not yours, the installation instructions do say that an air vent in the pinth should be fitted to allow the air to flow up and out of the top of the oven. Her's is about 8 years old as well.

I am a tad confused though. When you say it trips after two hours, do you mean that the oven will trip when turned on and empty? At a guess the oven has three heating elements, the one in the base, the grill on at the top and the circular fan at the back. You could always remove the wires to one of each and see what happens?

Other than that, checkout one of the dedicated "white goods" forums. This site is great but there are other specialised forums.

The gas hob plinth looks to be sealed around the marble worktop......although I'm thinking that there is a leak path, hence the issue.

It's tripped about 4-5 times in the last 6 months. Prior to last night, it tripped while cooking (with gas). Last night, somewhat bizarrely, it tripped at about 21h30 and plunged the house into darkness. In every case, the oven was not / had not been used so was cold.

When I tuned the power back on at the CU last night, the oven clock flashes. As soon as I press the "set clock" button, it trips again. If I switch the oven power off at the wall socket and wait overnight (for it to dry out), it all seems to work ok.

I'm a retired mech engineer so my training taught me that electrickery is the work of the Devil. Pretty safe to assume that I'm an electrical numpty. I don't know how to access the wires to the oven. The hob and oven installation looks impenetrable to my eyes.

Will google find a dedicated white goods forum?

Thanks for taking the time to post.

 

[Skylark NW]

"Steam from gas hob trips oven"
I'm curious as to how steam from cooking on the hob can affect the oven, which is below the hob? Isn't your kitchen vented? Is the oven supply switch/fused spur in the path of the steam?

Yes, the kitchen is vented and the gas hob has an overhead canopy with light, filter and extractor. Nevertheless, when cooking, there's plenty of steam/condensation and even a bit of boiling-over-the-saucepan so plenty of water........some of which is causing my problem, I think.

 

[Skylark NW]

Steam/moisture from the oven. Hob is unrelated.

I believe that it is steam/condensation/splash water arising from cooking with gas. In each case of tripping the consumer unit, the oven has never been in use, always cold.

 

[jj4091]

I had a similar strange oven tripping rcd problem a while ago, it turned out to be the back of the suppressor pcb. ( at the back of the machine connected to the supply cable ) intermittently shorting to the oven casing where it was mounted. May be worth checking.