Bosch hotplate tripping RCD

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Hello

I hope this post follows the rules - if not then please tell me.

I have a Bosch NCT615C01/01 electric hob, with three problems:

1. Switching on the rear left hotplate causes the RCD to trip in the fusebox.
2. The right rear hotplate doesn't get as hot as I think it should.
3. The left front hotplate doesn't get as hot as I think it should.

Do you think there's a common cause of these problems, or are they all separate?

I'd be grateful for any advice anyone can provide.

Thanks.

 

[jj4091]

The only common cause that I can think of is that the neutral to the rear left is somehow shorting to earth & possibly you have other burnt wires/connectors dragging down the voltage, I'm afraid it is difficult to say without seeing it.

 

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Surely if a neutral was shorting to earth then I would never be able to reset the RCD? Or are the control knob things all double pole?

And if that was happening, and the other hotplates were affected by "other burnt wires/connectors", then that isn't a common cause. Surely?

Or am I entirely misunderstanding?

If a hotplate is faulty does it get only warm and never really hot?

 

[flameport]

Heating elements either work properly or not at all, there isn't really any failure mode which could result in partial heating.

The controls are probably single pole.

Rear left - most likely a broken element where the insulation has failed causing part of the element to short to earth.

Others - not heating up enough would suggest a defective thermostat which cuts off before the element has heated up properly. The thermostat may be an integral part of the element or it could be a separate component.

Spare elements, thermostats and other items are probably available, but with all these faults it is probably more economical to replace the whole unit.

 

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OK, I'm definitely starting to lean in the direction of a new hob.

Does anyone have any recommendations for a new one?

The same Bosch model would cost £150-160, so if I take that as the budget, which is the best model to get, and which are the ones to avoid?

 

[Taylortwocities]

.

Does anyone have any recommendations for a new one?

Probably better to ask in the Appliances forum

 

[bernardgreen]

Has the hob worked properly since it was installed ?

Incorrect connection of the supply to the terminals of the hob may be the cause of this problem

 

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.

Does anyone have any recommendations for a new one?

Probably better to ask in the Appliances forum

OK, thanks - I've just done that.

 

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Has the hob worked properly since it was installed ?

Incorrect connection of the supply to the terminals of the hob may be the cause of this problem

It worked when new. It's faulty at the moment.

Why would this cause one hotplate to work apparently perfectly, but two of the others not to?

Please can you explain your reasoning?

 

[bernardgreen]

Many hobs have more than one terminal for the Live supply.

The terminal block may be like this

L1

L2

N

E

If that is the case with your hob then two rings will be supplied by N and L1 and the other two rings supplied by N and L2. ( Or the split may be one and three )

In the UK where almost all houses have single phase power most commonly the L1 and L2 are connected together and Live is connected to both. Neutral to N and earth to E

But in other countries and a very few houses in the UK there are two or three phases available in which case sometimes one phase is connected to L1 and a different phase to L2 to spread the load among the phases.

 

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Thanks. This is a three year old flat, and there is no question at all that it has a single phase supply.

 

[bernardgreen]

So maybe there is a loose connection on the terminal block if it does have more than one L terminal. This may have led to heat damage and charring with a resultant path to earth that is tripping the RCD

 

[bernardgreen]

There is a wiring diagram of this hob on

https://portal.bsh-partner.com/portal(bD1kZSZjPTAwOQ==)/PORTALFRAME.HTM page 47 figure 5

EDIT ( you have to go in via the Bosch site so screen shot below )

Which shows one version two neutral terminals and two live terminals and another version with one neutral and two live terminal. A 6 core cable is supplied with the hob and cores are paralleled to suit.

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• bernardgreen
• 27 Sep 2009
• 1

Can you provide a photo of the terminal block in your hob ?

 

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That web page isn't accessible to me - it says this: "No correct login".

Thanks for the other information and thoughts.

Now isn't a very good moment, but when I get permission I'll haul out the oven, remove the hob and take a photo of the connections.

 

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It looks like we're getting a new hob - I'm not allowed to "mess about with it if I don't know what's wrong with it".