Tripping rcd

[swes]

Hi ,
I have a friend that is having a problem with her rcd tripping at least 6 times a day,and over night.She has quite a big house and recently a new small extension,In this extension she had an extended ring to supply a dish washer ,tumble and washer.These were in the kitchen before but on the same ring.So im trying to iliminate the problem by shutting mcbs and using the old process of elimination.She has also had an additional fridge freezer put in this is a Range master which makes ice and cools water (not your average size either),Am i right in thinking this is an earth fault and not an overload problem as it trips the rcd not the mcb...
Thanks

 

[ColJack]

shutting off MCB's won't help you if it's a N-E fault.. the MCB's don't generally isolate the neutral as well unless you've got double pole MCB's for some reason..

 

[Taylortwocities]

Yes RCDs trip with an earth fault, not overload.

They also detect an earth fault on eaither line or neutral so you will not help yourself by just turning off the mcb to try to locate the problem as the neutral will still be connected.

You will need to remove the cabe from the neutral bus as well as the mcb.

Trying to do this by trial and error is a long, painful business,. You need an Insulation Resistance tester.

Edit: Also, have you determined when this problem actually started?? Sometimes they will say "about the same time that we bought that 42 inch Plasma TV........."

 

[swes]

thanks i have a calibrated megger 1502 and have done an ir test through the r1 ring but never thought of the rn i have recently got my part p certificate i know its not a proper qualification and in any way not a qualified spark so im still learning so any help will be gratefully recieved.The r1 came out at >1999 on all three ringts

many thanks again
Martin

 

[ColJack]

so you didn't think to do a N-E IR test along with the L-E and L-N IR tests?

 

[nozspark]

thanks i have a calibrated megger 1502 and have done an ir test through the r1 ring but never thought of the rn i have recently got my part p certificate i know its not a proper qualification and in any way not a qualified spark so im still learning so any help will be gratefully recieved.The r1 came out at >1999 on all three ringts

many thanks again
Martin

No it didn't...

The max reading on a MFT 1502 for a 500v IR test is >299Mohms

what test did you actually do??

 

[EdwardCurrent]

Hello.
Faulty or breaking down appliance.

Regards
Ed

 

[swes]

yeah >299 dur ! it was the 500v ir test i done sorry had a blonde moment, yes the house has 3 ring mains all in 2.5 t+e these three are the only ones on the rcd . so ill ir all three rings tommorro and get back to you . any other suggestions to find a fault I heard that there was no such thing as a nusance trip ???????????