Earth Fault on Cooker

[jffoz1]

Hi,
I tried to post this once, so if it's a repeat please accept my apologies.

I've just had to do some major rewiring in the house, to create two new ring mains. this involved disconnecting and continuity checking each and every plug socket, including the cooker. Thank God the cooker was on its own radial and so in effect all I had to do when the work was done is connect it back up. However, although all the other wiring is fine, when I recoonected up the cooker, it kept tripping the MCB or RCD. I systematically checked that I had 240v to the cooker socker and plug. Then I had 240v going into the cooker (both with cooker disconnected). But when I reconnect then cooker... TRIP!!!
The MCB is 40A. So the question is:-

Is the MCB big enough? I don't want to put a bigger one in and find that something starts to over heat.
Also I read that the cooker itself could be at fault. dust / moisture.
Could the Socket also be at fault?

 

[viewer]

If cooker OK before work and nothing altered or damaged on circuit, then it must be a problem within the cooker and a bigger MCB is not the answer. Assuming cooker not stored in wet, then good chance something has moved when you moved the cooker and you have a short.
Can you check resistance on the cooker internal circuits?

 

[JohnD]

... it kept tripping the MCB or RCD....

Please explain.

Do you mean that sometimes the MCB tripped, and sometimes the RCD?

Or do you mean they both tripped?

Or do you mean they kept tripping something but you don't know if it was an MCB or an RCD?

What sort of consumer unit have you got, and what devices does it contain?

 

[jffoz1]

Sometimes it was the RCD, but most of the time it was the MCB.

 

[JohnD]

look for damaged cable or loose connections. Might be the cooker cable when it was moved, e.g if the cooker was stood on the cooker cable and crushed it, or if the cable was yanked. Connect another high-wattage appliance (such as a kettle or toaster) to the cooker outlet to see if the problem is upstream of the cooker.


BTW it is preferable not to have a cooker on the RCD side of a split-load CU as they are prone to nuisance tripping. If not on an RCD then the cooker switch should have no socket on it.

 

[jffoz1]

Thanks for the advice. Took a systematic approach last night and found that there is likely a fault on the clock / oven timer. Having first checked the elements of the top grill and oven. Both seem to be showing reasonable resistance values.
When I disconnected the clock / timer supply, everything was 'hunky dory'. However when I turned the oven on (which has a link from the timer) just the MCB tripped. So I think I'm homing in on the problem.