RCD Fault???

[dolomite]

Hi everyone!!

Your thoughts on an issue I've come accross today please!!

MK consumer unit, split with RCD covering cct's 8-12. 32a MCB Put in a new cooker cct today in no9, 6mm T&E, single DP switch and a connector for the cooker. Cable run is about 10m's total.
R1+R2 ok, polarity ok IR's all over 299Mohms (Megger 1553 MFT).
All good so far.
No Trip earth loop test, the RCD trips. Same with PFC. Tried it a few times to make sure I've got the right leads in right places and they're connecting well, but it keeps triping.
I did a PIR there last week and checked the RCD then, all ok. Checked, checked and re-checked, always the same!!
Now I've connected the oven back in and as soon as the cct is live it trips. But connect into sockets, no problem!!
I'm left scratchin my head on this one. Any idea's? Am I missing something?

Got a new RCD to fit tomorrow to see if that makes any difference. Fingers crossed!!
Might be worth saying that the CU was fitted by someone a couple of years ago, but they left in a hurry never to be seen again. No excuse on my shiney new cct tho!!

Thanks all

Dolomite

 

[Des 56]

Why are you testing an rcd with an unreliable inappropriate "no trip" loop test

What was the results of conventional testing ?

 

[dolomite]

Sorry if I didn't make it clear, I'm not testing the RCD. I was conducting an Earth Fault Loop Impedence test, followed by a PFC test. The RCD was tripping even though the tester is set in the 'No Trip' made.
I can move the MCB so it is not on the RCD side (or loop it out), but surely this is self defeating as I will have to move it back again.

I was only asking for peoples thoughts or if they have come across this before.

Dolomite.

 

[Deleted member 9648]

Sounds to me like the N to the cooker is in the wrong bar.

 

[WayneL]

Sounds to me like the N to the cooker is in the wrong bar.

And me.

 

[vambo]

did you do the test with all the other circuit's isolated? there could be leakage from other circuit's which is bringing you upto and over 30ma. Otherwise it's the wiring config at the actual cooker as Wirepuller say's.

 

[dolomite]

Sounds to me like the N to the cooker is in the wrong bar.

Checked it first thing this morning. You were spot on!!
Serves me right for rushing too much, that I overlooked it!! DOH!!! Moved it to the other bar and all tested out fine!
Thanks all for your super quick responses!!

Dolomite