cooker earth fault

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daryl631

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fittted split load consumer unit today all went okay until checking cooker nuetral to earth fault checked wirirng all ok on megger test when disconnected from cooker, when connected to consumer unit tripped rcd so moved to non rcd side to try this stilltrips rcd,owner said had no faults before new consumer unit fitted,old unit was type 1 mcb,is it possible the cooker is at fault and how to explain this as owner said no faults previously.hope someone can help daryl

 

binky

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How old is cooker? Personally I don't like connecting cookers to RCD side of board because small faults with elements causes RCD to trip. Moving to other side of board should stop RCD tripping unles you forgot to move Neutral across as well. Old MCBs would probably not find fault, and certainly not one that RCD picks up, so not necessarily your handiwork. Go back in tomorrow and have fresh look at things. Check wiring again with cooker disconnected and check for damage to neutral cable from back box / fitment screws

 

SPECIAL LOCATION

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fittted split load consumer unit today all went okay until checking cooker nuetral to earth fault checked wirirng all ok on megger test when disconnected from cooker, when connected to consumer unit tripped rcd so moved to non rcd side to try this stilltrips rcd,owner said had no faults before new consumer unit fitted,old unit was type 1 mcb,is it possible the cooker is at fault and how to explain this as owner said no faults previously.hope someone can help daryl
Hi Daryl.....

1) I presume you have got a 250v option on your insulation Resistance tester?

You could do a 250v Ins Res test on the cooker alone.. dissed from everything else!

if there is a permanent fault on the cooker you will get a low reading to earth!

(& 250v test shouldn't knacker any bits off the cooker!)

2) Is the cooker isolator switch just a single switch or combined switch and socket?

If the cable is all ok and you have a socket, you can plug something else in to the socket on the cooker circuit just to verify to the customer that the supply cable is all working ok.

3) If there is a socket then it can be argued that it should be RCD protected.. one of those debatable areas..... until 17th enforced!!

4) Do I understand right from your post cooker wiring etc.. was all existing?

you only replaced CU?

have you double checked the physical connections to the back of the cooker?

I have seen some before where Joe public had struggled to strip and connect a 6mm....

butchered and hacked with bare bits here there and everywhere?

5) There aren't any other bits also connected to cooker circuit are there?

e.g. hob ignition? extractor hood etc.. with dodgy wiring?

6) Re putting back onto NON-RCD side.. as binky said ...

Moving to other side of board should stop RCD tripping unles you forgot to move Neutral across as well. Old MCBs would probably not find fault, and certainly not one that RCD picks up, so not necessarily your handiwork. Go back in tomorrow and have fresh look at things. Check wiring again with cooker disconnected and check for damage to neutral cable from back box / fitment screws
I would concur on all of these points. :)

and just to underline...

an MCB will not pick up earth leakage fault just overloads! :)

 

kme

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Evenin` all

Mr. Location. Your descriptive & salient points are, as usual, spotio onio (pidgin welsh, in honour of wizzer).

I won`t bother posting an answer - you & bink have just about wrapped it up, stuck the stamp on, and given it to the postmistress in the back room.

 

kme

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No m8 - I moon light as a postmistress...........!!!!!!!

:p :p:p:^O:O

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daryl631

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Thanks didnt have time to take the cooker out yesterday will check all this,original wiring to cooker only installed consumer unit the cooker switch doesnt have socket i will megger at 250v.

 
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