Steam from gas hob trips oven / consumer unit

[FrodoOne]

Picture of the consumer unit attached. The first black switch on the right, immediately to the left of the two red main switches, trips.
View attachment 247461

The "first black switch on the right" is is an RCD (Residual Current Device.)
(The next five "switches" are MCBs (Miniature Circuit Breakers) and you have FIVE of these "protected" by ONE RCD (Residual Current Device)

The use of ONE RCD "protecting" FIVE MCBs leads to the problem which you experienced and which "plunged the house into darkness. " (THREE other circuits - anyway!)

Last night, somewhat bizarrely, it tripped at about 21h30 and plunged the house into darkness.

Apart from you problem with "steam" causing sufficient leakage (somewhere) to cause an RCD to "trip", you have a Consumer Unit where multiple circuits are protected by ONE RCD, which causes another problem, when such an RCD is activated.

To avoid this in the future, it would be best if the two RCDs were removed and the RCDs replaced with RCBOs (Residual Current circuit Breaker with Overcurrent protection) - (See Post #4.)
Unfortunately, this will come at a cost (for replacement equipment - at least.)
However, if 10 RCBOs had been installed (in lieu of 10 MCBs plus 2 RCDs) in the first place, the cost may not have been significantly greater and the inconvenience of a fault on one circuit inactivating several other circuits would not exist.

(As an "aside", in Australia it is not allowed to have more than three circuits "protected" by one RCD.)

 

[Skylark NW]

Thanks, FrodoOne, for taking the time to clearly explain the innards of my consumer unit. The house was built in the 1980s and the consumer unit was only changed to the one pictured within the last 5 years.

To my relatively poor understanding of electricity, I haven't as yet understood the mechanism of failure but I'm very appreciative of all who have taken the time to respond, thank you.

I'll try one of the "wefixanyelectricalissue.com" trusted websites to seek a local tradesman.

 

[oldbutnotdead]

Unless you have a need for a big name oven, you may find it cheaper to buy a new one than to pay someone to try and trace the fault....

 

[EFLImpudence]

Residual Current (circuit) Breaker with Overload protection.

 

[Alec_t]

the gas hob has an overhead canopy with light, filter and extractor.

I'm thinking moisture accumulating inside the canopy etc could cause Earth-to-Neutral leakage which might be enough, or nearly enough, to trip the RCD. In the latter case, operating the clock set feature might somehow be the last straw and cause the RCD to trip.

 

[Harry Bloomfield]

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.

Does the hob ignition also work from the same circuit as the oven?

 

[jj4091]

Does the hob ignition also work from the same circuit as the oven?

Good thinking

 

[EFLImpudence]

...and the hood?

 

[FrodoOne]

Residual Current (circuit) Breaker with Overload protection.

Thanks.
We were both nearly right!

 

[FrodoOne]

The house was built in the 1980s and the consumer unit was only changed to the one pictured within the last 5 years.

I'll try one of the "wefixanyelectricalissue.com" trusted websites to seek a local tradesman.

Since of the ten MCBs only seven are labeled, it may (should) be that you have only SEVEN circuits in use - with three MCBs not connected to any circuit.
Hence if you do choose to replace MCBs with RCBOs, you may need only to contract for the replacement of the seven in use, at that time.

Then, if any additional circuit is added at any time in the future, the MCB concerned should be replaced at that time.

If you do replace only seven MCBs, it would be preferable to remove the unused MCBs and install "blank" plates.
"Blank" plates will be required for where the two RCDs are now located.

 

[Skylark NW]

Does the hob ignition also work from the same circuit as the oven?

No. There is a large red switch on the wall marked "cooker" and this only turns the oven on and off. With it switched off, the gas hob ignition, canopy light and extractor all continue to work.

The CU trips when cooking with gas only. Although it is powered (clock displaying), the oven is cold. When I reset the trip, the oven clock will flash 00H00. Only when I press "set clock" will it trip again, immediately. If instead I turn off the wall switch and wait overnight before turning it back on, I can set the clcok and all is well.

Could it be poltergeists?

 

[Harry Bloomfield]

No. There is a large red switch on the wall marked "cooker" and this only turns the oven on and off. With it switched off, the gas hob ignition, canopy light and extractor all continue to work.

Which is not really relevant - they could still be on the same circuit.

 

[Skylark NW]

Which is not really relevant - they could still be on the same circuit.

Ah, I see your point. I've just switched-off the MCB to the cooker. The gas hob ignition and overhead light and extractor still work.

 

[Harry Bloomfield]

Ah, I see your point. I've just switched-off the MCB to the cooker. The gas hob ignition and overhead light and extractor still work.

So, have we established yet what is actually tripping and what circuits the item is protecting?

 

[Skylark NW]

So, have we established yet what is actually tripping and what circuits the item is protecting?

I'm non the wiser, Harry. The RCB covering 5 MCB circuits, including the cooker, trips. most probably due to steam/water/condensation from above. It will reset and supply current to the oven clock but if I try to use the oven it will trip again. Wait overnight and all will be well.

Thanks for taking an interest in my problem.