rcd tripping when cooker turned on

riz99 · 28 Feb 2011

hi all,
just need alittle help, we've had a new cooker wired in, its an (induction one) now since the cooker has been wired up everytime you turn it on the rcd trips, not the cookers braker in the consumer unit just the rcd. The Rcd has tripped a couple times within the last few weeks for no reason, everytime re-tripped it its gone back on without any trouble, And now everytime we turn the cooker on it goes. Its an 63amp RCD which covers everything on the board. does anyone have any thoughts on what this could be as non of the wiring has changed its just been a stright swap of one cooker for another!!

ajrobb · 28 Feb 2011

For circuits above 32A, I think the RCD characteristics can be different to general circuits. If the cooker circuit cable is buried at least 50mm deep or has concentric earth protection, it might not need an RCD at all (except for TT supplies).

PrenticeBoyofDerry · 28 Feb 2011

does it trip as soon as the cooker is turned on? or after a while cooking.
Is there any particular element of the oven that is being used at the time it trips?
For example the grill, hob, oven.

riz99 · 28 Feb 2011

It trips as soon as you turn the cooker switch on! I havnt even see the lights on it or anything so cud even Be cooker as came out the packaging but i doubt it! Quite strange all I can think off is that with it being a induction cooker would this give it earth leakage when turned on? So do you think the cooker mob could be placed before the rcd to stop it tripping as The cables are buried at least 50mm it's the excising cables!!

MalcofArabia · 28 Feb 2011

Whoever wired it up could have reversed the Polarity ie Neutral/Earth and so just turning on the power will trip the RCD, check the connections, may even find it best to check the units terminals as well.

If that is not it then you may need to get an electrician in to ramp test the RCD to check what it is tripping at, and he will also check the Protective conductor current on the circuit.

RossR · 28 Feb 2011

riz99 said:
The cables are buried at least 50mm it's the excising cables!!

Are you sure? It's very unusual to find cables buried more than 50mm deep in a wall. You're not allowed to chase walls to more than one third of the depth of the wall (only counting a single leaf of a cavity wall). It only a sixth for horizontal chases.

echoes · 28 Feb 2011

The Rcd has tripped a couple times within the last few weeks for no reason

There is always a reason!

Did the RCD trip 'for no reason' BEFORE the appliance was installed? Or only since?

everytime you turn it on the rcd trips

Either a fault was introduced when the appliance was installed (Could be a pinched wire), the appliance itself might be faulty, or if the RCD was prone to nuisance tripping already, then you might have an existing fault, or a significant amount of leakage on other circuits connected to that same RCD, and the small amount of leakage caused by the new appliance is enough to push the RCD over its trip threshold.

You might be able to do a certain amount of detective work yourself if you know what to do and look for, but an electrician with the test gear should be able to isolate the problem extremely quickly.

By the way, is this an induction HOB, or a complete cooker with oven, grill and everything?

EFLImpudence · 28 Feb 2011

May be of help.

Had the very same thing last week.
Connect brand new free-standing cooker to existing cable.
Continuity fine.
Insulation Resistance fine - all >500MΩ
(also Loop OK)

All RCBO CU
Connect cooker - all cooker switches off.
Switch on RCBO - OK
Switch on CCU - trip

Because it is RCBO cannot tell if Over-current or Earth leak - Is there any way to tell???

Tripped again, tried allsorts to find a problem - all SEEMS OK.

Took back off cooker - looks fine.
Put back on cooker - tried again - All working as it should.

Can only assume it was a trapped wire but don't really know.

JUST BECAUSE THINGS ARE NEW DOESN'T MEAN THEY'RE FAULTLESS

PrinceofDarkness · 28 Feb 2011

I agree with 'echoes' here. This might not be a fault with the new appliance at all. The very act of switching on one appliance can trigger a latent fault on a different circuit........

Only a thorough and methodical process of elimination will reveal the true fault if you have no test instruments.....

Lucia.

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rcd tripping when cooker turned on

PrinceofDarkness

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