Cooker circuit tripping rcd

[Tankerman]

Hello All,
I have a question regarding our new kitchen refit and cooker. We had a fantastic new kitchen fitted and a new Smeg Range cooker with an induction hob.

The electrian rewired the kitchen and installed a new cooker circuit. Th cooker keeps tripping the rcd even when it's not on! The cooker draws a maximum of 19.5 kw so a 10 mm cable has been run connected to a 50amp mcb. But it kept randomly tripping the rcd so he tested everything and found the rcd was over sensitive so he swapped them over which seemed to cure the problem for a while now the problem is back. He has told us that the CU is quite old and parts for it are no longer available (it's a Square D quicklime 2) which I believe are now manufactured under the Schneider brand. He has said the only answer is a new CU which I don't mind replacing it's just it's a lot of expense for one RCD.
Could this be my only option.
Thank you in advance.

Colin

 

[EFLImpudence]

You need to find the fault first.

It seems there is a Schneider alternative.
https://uk.rs-online.com/web/cpd/3405098/

 

[Iggifer]

No need for a new CU, although (it's been a while since I've worked on a split load Kwikline so I may be wrong) if I'm not mistaken, somebody has fitted an RCD in place of the main switch, so the RCD on the left is protecting the entire installation, and then the RCD on the right is doubly protecting the cooker and your other sockets, which is incorrect.

Which of those RCDs is tripping? If it's the one on the left, it could be a whole host of issues not just the cooker.

 

[ban-all-sheds]

Th cooker keeps tripping the rcd even when it's not on!

If it's off how do you know it's responsible for the trip?

 

[Tankerman]

The cooker is on its own separate circuit so if I leave that mcb off everything is fine and I've had the appliance tested and it's not that.

 

[Iggifer]

Which of those RCDs is tripping? If it's the one on the left, it could be a whole host of issues not just the cooker.

 

[davelx]

) if I'm not mistaken, somebody has fitted an RCD in place of the main switch, so the RCD on the left is protecting the entire installation, and then the RCD on the right is doubly protecting the cooker and your other sockets, which is incorrect.

I don't think we can be sure without seeing inside - it may have been internally altered so that the two RCDs are both fed direct from the incoming tails.

 

[Iggifer]

I don't think we can be sure without seeing inside - it may have been internally altered so that the two RCDs are both fed direct from the incoming tails.

True but that would be non compliant without an external isolator as there’s no main switch for the installation.

 

[ban-all-sheds]

The cooker is on its own separate circuit so if I leave that mcb off everything is fine and I've had the appliance tested and it's not that.

Some (all?) induction hobs contain power supplies which intrinsically leak to earth, so it could simply be that that, plus the cumulative leakage from all the power supplies in TVs etc plugged into the downstairs sockets are adding up to enough to trip the RCD.

But back to this:

Th cooker keeps tripping the rcd even when it's not on!

Are you saying that as soon as you turn the cooker MCB on the RCD starts tripping even if the cooker isn't running?

 

[jj4091]

What is the make & model of your cooker?

 

[davelx]

True but that would be non compliant without an external isolator as there’s no main switch for the installation.

We don't know there isn't one though, do we? We only have a picture of the CU.

 

[ban-all-sheds]

What is the make & model of your cooker?

One half of that Q is easy to answer:

a new Smeg Range cooker with an induction hob.

 

[Tankerman]

Here is another photo of the main switch

 

[Iggifer]

Which RCD is tripping?

 

[Iggifer]

We don't know there isn't one though, do we? We only have a picture of the CU.

Points for whoever did change it round as there is