Tricksy electrical problem... please help!

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Having an electrical nightmare… any tips / advice very welcome!

A bit of background: We had our kitchen replaced a month or so ago and have had electrical problems ever since… specifically, the RCD keeps tripping, which then cuts power to everything else. Not nice first thing in the morning… the RCD trips most often when the shower is used, but it’s also happened when the heating comes on.

We turned off everything electrical in the new kitchen – lights, sockets, hobs, extractors, fridge and ovens (to keep the wife happy we replaced a single double oven with a main oven / steamer / microwave thing, a relatively standard top oven, and a warming drawer - each on their own isolation switch). We then added each element back in progressively.

Long story short, shower works without tripping the RCD until the ovens are added into the mix. When the ovens are switched to standby (but not actually doing anything) at their isolation switches, the RCD trips pretty much immediately, or very soon after, the shower starts to run.

So we then tried each oven individually…
- Main oven on standby, top oven off, warming drawer off – no RCD trip when ensuite shower used. All good.
- Main oven on standby, top oven on standby, warming drawer off – RCD trips when ensuite shower is used
- Main oven on standby, top oven off, warming drawer on standby – RCD trips when ensuite shower is used
- Main oven on standby, top oven off, warming drawer on standby – RCD trips when other shower is used (in main bathroom)

The ovens and shower are all on the main circuit (which has the RCD).. none of the other circuits for lights, sockets etc. are effected… We also have an extension to the house, with a separate Consumer Unit – this is not impacted at all.

The sparky is fairly flummoxed.... any pointers very welcome…!

Cheers,
UV

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hairyben said:

You can have earth faults that wont trip the rcd, ie present enough earth leakage untill something unrelated is consuming current on the circuit.

Is the spark any good? A lot of reasonablish cable installers offering electrical installation really arent up to fault finding, have the analytical mind for it.

Thanks - spark seems helpful, but I'm not confident he has a solution yet apart from "replace the ovens"...

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Blaster72 said:

Have you tried a brand new RCD? Yours could have been just on the edge before and the new appliances have tipped it over into tripping falsely.

Hi.. I'm looking at this as the last resort as, from what I understand, the RCD is usually the least likely cause and the testing suggests its related to the ovens and other devices on this circuit...

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eldar said:

Shower and Cooker earthing or polarity - has any wiring been done on it? And anything else on that circuit that has been touched.

Hi, that was my thinking also.. most of the kitchen and dining rooms was touched - new lighting in ceiling*, LED strip lights under peninsula*, new fridge*, new hob, new extractor, replacement dishwasher and the pesky new ovens.

Any ideas what the solution might be?

cheers,
UV

• these all required extensive additional wiring that was not there previously

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All

Thanks for the tips and pointers so far... will look into what testing has been done, and look to put in place individual RCBOs if only to mitigate the impact when the issue occurs. Cable guy is coming back round this week, then the spark, so hopefully will be able to get to the bottom of it..

cheers,

UV

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CorradoTDI said:

Sounds like an earth issue rather than load...

It's likely the oven is faulty and has an earth leakage in standby - what brand is it??

Hi, it's NEFF so that would be disappointing!

Cheers,
UV

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Murph7355 said:

Thirded.

OP, I would do this as a matter of course with the way you describe things. (In fact I did just that a few years ago ). It may not in itself fix the problem, but will be less of a ball ache when things trip and will give a stronger indication of what is actually failing. IIRC it wasn't that expensive to do.

Ref your oven and shower....how far are they/how long are the cable runs from the consumer unit?

Thanks - RCBOs definitely seem like the logical next step. The cable runs aren't massive - no more than 15 metres I would say...

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brman said:

Only if he is lucky! IR testing.... so it never hurts to get a 2nd opinion.........

Cheers, sounds like you've been there and done that... I may PM you if you're able to help and near Bromley - the spark now seems to have gone AWOL...

The kitchen fitters have been back and checked the wiring... from their point of view, all the appliances are connected correctly.. so down to our wandering spark now to see what he suggests as next steps...

thanks

UV