DIY - new oven tripping DB.

[Jim Goodenough]

hello all,

btw I'm a plumber.... do I hear groans?! I installed a new Neff oven, DB is 0.5m away through a wall, wired into spare 16A MCB (house was built 2019) with 2.5mm T&E via 20A switched outlet, manufacturers lead with moulded plug (wired into outlet - not shortened).

... plug lead into oven... pop... both RCD's trip.
... switch outlet on... ditto
... switch MCB on... ditto

Neff engineer came out, no difference... tripping RCD. Tested the oven with his test lead plugged into ring-main, absolutely fine, no issues. Conclusion: is the Neff lead is faulty, OK. (No replacement lead on vehicle!) replacement lead sent via courier turns up 4 days later.

... wired up new lead... pop... same issue.
OK, wired up original lead Neff into plug; plugged into extension lead, plugged into ring-main... oven fires up, no issues!

What am I doing wrong?? Is the 16A MCB faulty? Do I need to check continuity of 2.5mm T&E?

Please help...

Regards
Jim

 

[westward10]

If both RCDs trip I assume this is a dual RCD board, have you connected the neutral to the correct bar.

 

[Jim Goodenough]

If both RCDs trip I assume this is a dual RCD board, have you connected the neutral to the correct bar.

Oh, would you believe it... moved neutral to other bar and NO ISSUE.....
How did you know that... ? & why does (did) it trip...?
Thanks so much.

 

[littlespark]

Oh, would you believe it... moved neutral to other bar and NO ISSUE.....
How did you know that... ? & why does (did) it trip...?
Thanks so much.

How do we know?

It happens countless times, and it’s always first thing we check.

As to why it trips…. Everything has an electrical load, in amps… as you may know.
An RCBO, or RCD basically measures what the load is on the live, and the neutral. If there’s a difference of 30mA, as standard, it will trip.

What you had was the life of the circuit going through one rcd, and the neutral going through the other…. So neither was balanced…. Rcd trips.

 

[Mike Johnson]

Neff engineer came out, no difference... tripping RCD. Tested the oven with his test lead plugged into ring-main, absolutely fine, no issues. Conclusion: is the Neff lead is faulty, OK. (No replacement lead on vehicle!) replacement lead sent via courier turns up 4 days later.

And Neff had the cheek to call him an engineer, perhaps he was a mechanic.

 

[littlespark]

That’s not fair on the Neff engineer.

He only knows his specific product, and probably has to follow a troubleshooting guide that Neff themselves has written.

They just assume as mains socket outlet works… as it would with a plug in tester.


It would be like asking a dentist to have a look at your feet.

 

[Jim Goodenough]

How do we know?

It happens countless times, and it’s always first thing we check.

As to why it trips…. Everything has an electrical load, in amps… as you may know.
An RCBO, or RCD basically measures what the load is on the live, and the neutral. If there’s a difference of 30mA, as standard, it will trip.

What you had was the life of the circuit going through one rcd, and the neutral going through the other…. So neither was balanced…. Rcd trips.

TYVM @littlespark, I hate being beaten! Well, I'll never make that mistake again....

 

[Jim Goodenough]

And Neff had the cheek to call him an engineer, perhaps he was a mechanic.

He was a nice bloke... and he did test the polarity at the outlet...

 

[westward10]

I presume you have notified the installation of this new circuit to Building Control.