Cooker Tripping RCD on CU

[barch]

Hi All.
I've had a look thru the forum for similar issues to the one I'm having. My cooker trips the RCD on the consumer unit after a very short time of being on. I've taken both the grill element and oven element out and I'm going to replace both or either. I've connected a meter to the contact points and get the following reading:-
OVEN ELEMENT, 47ohm resistance.
DUAL GRILL ELEMENT. 56ohm on one circuit, 32ohm on the other.

I'm not sure how important it is, but when I connect the mulitmeter, only the smaller element on the dual grill "buzzes". Does this make sense? And is there anyway of me telling with the meter which one needs to be replaced?

thanks

 

[JohnD]

does it trip when you turn one of the elements on, or at other times?

does it have electric or gas rings on top?

 

[jj4091]

The easiest way to tell if one or both the elements are breaking down is to disconnect them one at a time & see if it makes any difference. It is a common problem for oven element insulation to break down & trip the rcd. In fact cooker switches are often connected to the non rcd side of a consumer unit.

 

[Leccy758]

Check the resistance between the element and earth with the wires disconnected.
Not too accurate unless you have a Insulation tester or it has just tripped when heating but it may show an element that is leaking to earth.

 

[barch]

thanks for the answers guys. I had hoped one of the elements was faulty but this doesnt seem to be the case. I've turned of every other circuit breaker and left just the oven one on and, you've guessed it, oven gets up to temperature. No tripping. (I can almost smell cake!) So it appears that there is a enough leakage current to trip the RCD in all the circuits. Think it may be time to call one f the professionals in!
thanks for the help

 

[mjjuk]

Could be a faulty RCD

 

[barch]

Time to revisit this again I'm afraid

Our cooker is still not working. To be on the safe side, I have had installed in the CU a separate RCD for the cooker. It still trips so I've ruled out a combination of earth leakages from around the house.
I've taken the back of the cooker and you'll see in the following pics what I found by putting a multimeter across the terminals. There are three elements. 1 around the fan, A grill or top oven element and the bottom element. Firstly, it doesnt seem to matter on what setting we have the cooker be it grill, top oven or bottom oven, t trips when it gets to a certain temp.
It stripped when I fiddled with the temp controller on the front panel but that might just have been coincidental

So, I buzzed out all the contacts on the wiring loom. For the top oven/grill element, the two inside connectors for the inside loop buzzed out and gave a reading of 56.6 ohms. The two outside ones provide a much higher resistance reading, but the multimeter doesnt buzz Why would this be?

All of the other elements buzz out giving readings that are similar to each other, its only that one loop that varies greatly from the others. However, when I disconnect that loop, and turn the oven on, it still trips the RCD.

Could it be the temp switch on the front panel? Or should I go ahead and change the top element and see what happens?
thanks

 

[Ric2013]

I'm not an electrician, so bear that in mind, but shouldn't you be testing the resistance to earth rather than across the elements? After all, an RCD detects an earth leak... though I dare say this post comes 2 years too late!

Leccy758 and others have already suggested this, but your pictures clearly show you testing everything but resistance to earth.