Large oven tripping RCD

[al1981]

Hi all.

Looking for a bit of advice.
Customer has a new large induction rangemaster cooker with a total power of 14.8kw.
Currently on a Hager board with a 50a b mcb and an existing 6mm cable.
As soon as oven was switched on it tripped the RCD.
Taking diversity into account the cable should be fine.
Is the breaker too large?
Insulation resistance test comes back fine.
Should I try a smaller breaker?
The oven has the potential to pull 60 + amps and they’ve said they want all 3 ovens on and the hob so I’m wondering if it needs it’s own 63a RCD and a 10mm?

I don’t want to stick it on a 40a and have issues later on.
I guess there’s also the potential that the element had gone as well?

 

[DPG]

OP, Is this your normal line of work?

 

[Pete999]

OP, Is this your normal line of work?

Doubtful Mate.

 

[dmxtothemax]

Having a Blonde moment Mate, please explain for an Oldie.

exactly that ! being a large inductive load, it would have an effect effect on power factor, and if power factors get too high, they can trip the RCD.

 

[Pete999]

exactly that ! being a large inductive load, it would have an effect effect on power factor, and if power factors get too high, they can trip the RCD.

So you are saying that if something has a near unity PF it can trip an RCD?

 

[telectrix]

think he means if the PF is below unity, e.g.0.8 or less. i'd like to know why it might cause rCD tripping though. in this situation, I'd shift the oven onto a 40A RCBO and see if it held.this would eliminate cumulative leakage.

 

[Pete999]

think he means if the PF is below unity, e.g.0.8 or less. i'd like to know why it might cause rCD tripping though. in this situation, I'd shift the oven onto a 40A RCBO and see if it held.this would eliminate cumulative leakage.

Yeah me as well but I was being or trying to be diplomatic.

 

[Jim Cartledge]

As an RCD is a current operated device, why would the 'power factor' have anything to do with it tripping? The power factor is related to the cosine of the angle between the voltage and the current.

 

[Pete999]

Yes figures on the IR test. And test the appliance too. In fact, do that first. After you have corrected the MCB size on that circuit.

Oh hold on. If you are a trained electrician, you really need to check your college notes. You have forgotten some essential basic things.

College notes?

 

[Dustydazzler]

Technically speaking 6mm cable of a 50a mcb is a no no , it either needs to be 10mm or reduce the mcb to a 40

But I have seen an experiment done by J.W where he gets some 1.5mm clipped direct cable to draw very near 70 amps for a considerable length of time before starting to smoke.

Back to the OP , my single build in oven has the strange tendency to trip my house rcd from Time to time

 

[Pete999]

As an RCD is a current operated device, why would the 'power factor' have anything to do with it tripping? The power factor is related to the cosine of the angle between the voltage and the current.

An RCD operates on earth leakage, Jim, it is not an OCPD!

 

[DPG]

An RCD operates on earth leakage, Jim, it is not an OCPD!

But still current operated.

 

[richy3333]

Well the OP hasn’t been back so I guess the house burnt down

 

[Jim Cartledge]

An RCD operates on earth leakage, Jim, it is not an OCPD!

It operates on Residual Current i.e. the in-balance between Phase and Neutral. So what does that have to do with power factor?