Britannia SI-9S – Tripping 32A RCBO after ~1hr

[BenBarker]

Hi All – recently joined and very impressed with how knowledgable everyone is. We’ve purchased a 2nd hand Britannia SI-9S. We’ve been assured it was all working before purchase, but now we’re encountering an issue. It has a full size electric fan oven and a half size convention only oven. The small oven works fine in any situation, but the larger oven trips our 32A RCBO after running for 30-60 mins. The oven is on its own ring. Mostly it appears to link back to the fan, but not entirely:

• The oven only trips once it has reached around 150c, and then only when the fan is on
• Once it has tripped and restarted the clock (so it flashes), everything related to the large oven trips it, even just putting the light on
• If the clock is reset (so it no longer flashes) the convection oven can be used again
• Fan related modes will immediately trip it until the oven has cooled

So as it stands:

• Main oven fan modes are unusable once above ~150C
• Once RCBO has tripped, all main oven functionality trips RCBO until clock is reset
• Once clock is reset all non fan oven functionality works again, even upto 250c on both ovens
• Secondary oven functions entirely as expected – even running rotisserie mode + main oven on convection simultaneously

I’m wondering:

1. Is our oven overrated for our oven ring?
2. Do we have a faulty fan, if so why is the tripping of other modes related to the clock being set or not
3. If we have faulty fan, why do the fan modes only trip after 30 mins+ of heating
4. If it isn’t the fan, why do all non-fan modes work if the clock is set (not flashing)?

Anyway, that’s where I’ve got to with trouble shooting. Thanks for reading and any help much appreciated.

[electrofix]

you have one faulty element the has high earth leakage when hot. when it cools down the rcbo can be reset

an RCBO is both a fuse (MCB) and an earth leakage circuit breaker and in this case its not a fuse rating problem it an earth leakage problem

Dave

[BenBarker]

electrofix wrote:you have one faulty element the has high earth leakage when hot. when it cools down the rcbo can be reset

an RCBO is both a fuse (MCB) and an earth leakage circuit breaker and in this case its not a fuse rating problem it an earth leakage problem

Dave

Thanks for the response! Ignoring the clock issue, it seems that it’s the fan modes that are tripping the oven when hot. Does that mean it makes sense that the fan is faulty? What’s the best way to troubleshoot?

[electrofix]

the fan element is most likley faulty. I have had fans go but not often

the only way you know for certain is either swop it or measure the insulation resistance of the element while its hot

Dave

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